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Have you been looking `for an amortization schedule to handle a loan feature that other web calculators can't accommodate?

Or are you looking for an amortization calculator which is easy to use yet provides you with tons of details including the ability to set the original loan date followed independently by the payment start date?

Or are you looking for an amortization calculator that can create professionally printed schedules from any device?

If so, then this is the calculator for you. Scroll down the page, and below the calculator, you'll find all the options and features explained.

If, on the other hand, what you want is a quick schedule, then here is all you need to do...

Steps for a Quick Payment Schedule

  1. Leave all inputs and setting set to their defaults
  2. Enter the "Loan Amount"
  3. Enter expected "Number of Payments"
  4. Enter the "Annual Interest Rate"
  5. Set "Payment Amount" to "0" (the unknown)
  6. Click either "Calc" or "Print Preview" for your schedule

That's it! That's all you need to do to create a standard loan schedule.

But what if the terms of your loan do not conform to this calculator's default settings? Or what if you want to know what amortization method will save you the most in interest charges?

Then keep reading. All the options, as well as the nine types of amortization schedules this calculator can create, are explained below...»

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Related: Need even more flexibility? Need to create an adjustable rate loan or mortgage (ARM)? Need to enter regular or irregular extra payments? Need to amortize a construction loan? Then use this financial calculator. Users can enter multiple loan advances and adjust payment amounts and interest rates on any date.

What is amortization?

According to Wikipedia "Amortization refers to the process of paying off a debt (often from a loan or mortgage) over time through regular payments. A portion of each payment is for interest while the remaining amount is applied towards the principal balance."

Further, "an amortization schedule is a table detailing each periodic payment on an amortizing loan (typically a mortgage), as generated by an amortization calculator."

(To be technical here, I take issue with the use of the word "regular" as used in the definition. I prefer "periodic" or "recurring" instead. Perhaps I should edit the entry?)

That's what amortization is, but the definition does not address, naturally, the different methods used for calculating an amortization schedule.

This calculator does!

It supports the following nine amortization types.

  • Normal Amortization
  • Rule-of-78s Payment Table
  • Interest Only Payment Schedules
  • No Interest Loan Schedules
  • Fixed Principal Amortization
  • Canadian Loan Schedule
  • Amortization with Points & Annual Percentage Rate (APR)
  • Loan Schedule with Final Balloon Payment
  • Negative Amortization

You'll find each method discussed below.

But, before we discuss how to create the various loan tables, I need to point out some essential options impacting the initial period's interest calculations.

About Dates, First Period Interest & Year-End Totals

Important Note About Dates: This calculator supports variable length first periods. That is, the calculator calculates the exact amount of interest due even when the initial period is shorter or longer than the other scheduled periods. Supporting odd length first periods results in more accurate calculations, but you'll see interest charges that do not match other calculators. If you want to match other calculators, then set the "Loan Date" and "1st Payment Date" so that they equal one full period as selected in "Payment Frequency." Example: If the "Loan Date" is May 15th and the "Payment Frequency" is "Monthly," then the "1st Payment Date" should be set to June 15th, that is IF you want a conventional interest calculation.

Click on "Settings" for "Long / Short Period Options"

Long first period

A long first period occurs when the period between the loan date and the first payment date is longer than the selected payment frequency. The calculator can calculate the interest due for these extra or odd days in one of four ways.

interest options
Under "Settings" — Long / Short Period Interest
  • None - free money! No interest calculated on the odd days
  • With first - odd day interest paid with first payment due. Payment will be larger than the other periodic payments.
  • With origination - odd day interest is due when the loan originates - commonly known as "prepaid interest"
  • Amortized - a small amount of odd day interest is paid with each payment. The calculator increases all payments to be equal.
long period interest options
Initial odd days interest paid with loan origination

Short first period

A short first period occurs when the period between the loan date and the first payment date is shorter than the selected payment frequency. The calculator can calculate the interest due for the short period in one of three ways.

  • No payment reduction - the calculator calculates what is considered to be a "normal" normal payment amount and uses it for the first payment. The last loan payment is reduced to compensate for the short period
  • Reduce first - the first payment is reduced to compensate for the short period
  • Reduce all - all payments are reduced to compensate for the short period.
short period interest options
Initial short period - first payment reduced

Here's a more formal definition of odd days interest from the Financial Dictionary.

One more comment about dates.

By default, the schedule's totals are calculated as of December 31.

But some taxpayers pay taxes based on a different year-end. This calculator supports annual and cumulative totals as of any month end.

Click the "Settings" button and select "Year End Month."

select the fiscal year end
Select the month for year end totals

9 Types of Loan Amortization Schedules

amortization methods
Six of the nine amortization methods

Normal Loan Amortization

If in doubt, use this setting when amortizing a loan. In the US at least, nearly all loans use the "normal" method.

These are the characteristics of a normal loan or mortgage:

  • They have "level payments" i.e., the scheduled periodic payment amount does not change. (With the possible allowance, as discussed above, for odd day interest.)
  • The interest amount paid declines each period as the loan balance is being paid down.
  • Thus, the principal amount paid each period increases to keep the payment amount level.
  • There may be a slight adjustment ("rounding") of the final payment so that the loan is brought to a 0 balance.

The next method, consumers will want to avoid.

Rule-of-78s Payment Schedule

The Rule-of-78s method front loads the interest due. That is, the debtor pays more interest early in the payment schedule and less interest later when compared to a "normal" loan.

Both the periodic payment amount and the total loan interest due are the same for both the Rule-of-78s and the "normal" methods. The only difference is how the interest gets allocated each period.

The blog post here thoroughly explains the Rule-of-78s amortization and why, as a consumer, you may want to avoid such loans.

For the lowest periodic payment, get a loan using the next payback method. There's only one catch...

Interest Only Amortization

Some loans require the borrower to pay only the interest due each period. Such loans are known as "interest only loans"

These are the characteristics of an interest only loan or mortgage:

  • The periodic payment amount generally does not change.
  • The interest amount paid each period is the same because no principal is paid, the loan balance does not change.
  • The entire principal balance plus the last period's interest is due with the last payment.

If you think that interest only loans are not very common, then think again.

Many bonds sold to investors are interest only loans. The bond's buyers are lending the issuer money. The bonds pay the buyer a periodic coupon payment which is the interest on the debt. And as reported by Zacks the size of the bond debt in the US at "the end of 2017 was more than $40.7 trillion"

That's a lot of debt financed with interest only payments!

If you represent a bond issuer, you can prepare a bond coupon payment schedule with this amortization calculator. The "loan date" is the bond's issuance date and the "first payment date" is the date of the first coupon payment. Make sure to select the "Interest Only" amortization method.

interest only amortization
Interest only periodic payment

No Interest Loan Amortization

Yes, it happens! I added this amortization method to the Windows version of this calculator 20 or more years ago. Someone called me (remember phone calls?) and said he and his wife were lending money to their son and they wanted to create a payment schedule that they could agree to, the catch was, there would be no interest charged.

This amortization schedule continues to support an interest-free loan.

You may ask, "Why not just enter a "0" interest rate?"

The answer is simple. If a user enters a "0" for any input, then the calculator interprets that as the unknown value. So if a user enters a "0" for the interest rate, the calculator will attempt to calculate the rate.

To get around this, select the "No Interest" option for an amortization method.

no interest amortization
No interest loan

The following amortization method will save you interest charges if you can afford it.

Fixed Principal Loan Table

Before computers and calculators, that is, before it was easy to calculate a level payment amount, lenders frequently had lenders payoff loans using the fixed principal amortization method.

Why?

Determining the payment amount requires only simple arithmetic. To calculate the payment due, first, divide the principal loan amount by the number of payments in the term and then add the periodic interest.

These are the characteristics of a fixed principal loan or mortgage:

  • Payment amount start higher than a "normal" loan.
  • The loans feature a declining payment amount. As the borrower pays down the principal balance, the interest due each period is reduced and therefore the payment decreases over time.
  • The principal amount paid each period is fixed. The principal paid on a $1,200 loan with a term of one year will always be $100.
  • The borrower pays less total interest
  • There may be a slight adjustment ("rounding") of the final payment so that the loan is brought to a 0 balance.
fixed principal payment loan
Fixed principal amortization - principal amount paid remains constant

Canadian Amortization Schedule

The Canadian amortization method is the same as the "normal amortization method" except for one detail. When the user selects the Canadian method, the calculator automatically sets the payment frequency to monthly and the compounding frequency to semiannual.

A conventional loan typically uses the same frequency for both payments and compounding.

The Canadian method, because it uses less frequent interest compounding, results in a slightly lower scheduled payment amount because the interest due is somewhat less each period when compared to the interest charges owed under monthly compounding.

For more details, here's a A Guide to Mortgage Interest Calculations in Canada.

Amortization with a Balloon Payment

Occasionally, there are times when the terms of a loan call for a payment to be calculated on a 30-year payback but the loan will come due after five years of payments (for example).

Because the payment calculation uses a 30-year term, the balance of the loan will still be substantial relative to the starting balance when the term is up in five years, and the balance is due.

Creating an amortization schedule showing the balloon payment amount is simple with this calculator.

  • First...
    1. Enter the loan amount
    2. Enter the interest rate
    3. Enter the number of payments which will be used to calculate the periodic payment due - in this case 30-years or 360 monthly payments.
    4. Enter "0" for the payment amount and click on "Calc"
  • Then....
    1. Change the number of payments to the actual term of the loan - per this example that's 5 years or 60 payments
    2. Click on "Print Preview" to see your amortization schedule with a balloon payment.
loan with a balloon payment
Loan amortization showing the balloon payment

Related: Need to calculate a regular periodic payment amount that results in a specific final balloon payment? Then see this site's balloon payment calculator. It creates a schedule too.

Loan Schedule with Points, Fees and APR Support

Some loans require the borrower to pay an upfront charge called "points."

Why would a borrower be willing to pay an extra charge?

When the borrower pays points, the lender reduces the interest rate. Points are in essence prepaid interest (and the IRS treats them that way). One point is one percent of the loan amount. Thus, one point on a $300,000 is equal to $3,000.

The user has two choices for how to create an amortization schedule with points. Click on "Settings" and select "Points, Charges & APR Options."

If "Include dollar value of points in interest charges" is checked then the calculator calculates the dollar cost of the points, and the payment schedule shows them paid at the loan origination. The calculator also adds the cost of points to the total interest charges.

If the user didn't check this option, then the dollar value gets reported in the header only, and the amount does not get added to the total interest.

See Moving.com "What Are Mortgage Loan Points?" for more details.

Points impact the loan's annual percentage rate. If you want to check the APR (and if you are the borrower, you should), you can include a Truth-in-Lending Act compliant calculation in the schedule's footer. Just check the option "Include Regulation "Z" APR Disclosure calculation at the end of the schedule?". For an accurate APR, don't forget to include any fees in "Other charges & fees (for APR calculation)?" input.

Related: If you have any questions about APR calculations and what fees to include or exclude, see this site's APR Calculator and Disclosure Statement. This calculator calculates APR and creates a printable disclosure statement.

points, fees and APR
Loan table with points, fees and APR options

Negative Amortization Calculation

Users frequently tell me they use this calculator to "check their lender's payment amount."

That's fine, of course. But all borrowers should also understand, there is no such thing as a "correct payment amount." The only payment amount of concern is the amount agreed to between the lender and borrower. All things being equal if the lender says the payment is $315 a month and the borrower expects it to be $311 a month, it doesn't matter - as long as they both agree on the initial period's calculated interest amount. If the parties agree on the interest calculation, then paying a slightly higher amount will pay the loan off marginally faster or result in a smaller final payment, and the total collected as interest will be slightly less.

So what does this have to do with negative amortization?

Simple, if the lender and borrower agree on an amount that is not large enough to pay the interest due it results in negative amortization.

This amortization calculator gives the user the ability to set any payment amount. Rather than enter a "0" for the payment, enter the agreed upon payment amount.

When the payment amount is less than the periodic interest due, the loan balance will increase each period because the interest not covered by the payment must get added to the balance.

There is nothing wrong with a negatively amortizing loan per say. However, the borrower will have to be prepared to pay a single, large payment at the end of the term.

If you are the borrower, be sure to check the last payment row of the schedule for the final payment amount, which includes the accrued interest, to see if you can handle it.

Note the negative principal amounts in the below figure.

A negative amortizing loan
Loan schedule showing negative amortization - loan balance is increasing

Need an Amortization Schedule in MS Excel®?

From time-to-time, I get requests from users for the ability to export an amortization schedule to Excel. This calculator won't do that. However, users can select the data and copy/paste to Excel.

You can copy/paste from either the main window or from the print preview window. If you copy from the main window, then formatting will remain intact. If you copy from the print preview window, then only the values will be copied. Depending on the browser you are using, you may have to use Excel's Paste Special feature and select "Text" for copy/paste to work.

If you want to copy from the main window, I think the easiest way to do that is to scroll to the end of the schedule and select the last row and then scroll upwards to select the entire table.

Related: My C-Value! for Windows program is even more flexible than this calculator and it will export directly to Excel.

amortization schedule in Excel
Select the schedule so you can copy / past to Excel

Save Payment Schedule to PDF

If you want to share this calculator's schedule with someone or save it in a digital format for later reference, you can print the results to a PDF file.

If you are using Google's Chrome browser, printing to PDF is a standard feature. Click on Chrome's menu (the 3 verticle dots) and select "Print..." Click on the "Change..." button and select "Save as PDF."

If you are not using a browser that supports printing to a PDF, no problem. You can install a PDF print driver. It pretty easy to do this. And there are many free ones from which to pick. In the past, I used PrimoPDF.

By the way, one advantage of installing a PDF print driver, even if you use Chrome, is you'll then be able to create PDF files from any application you use, not just your browser.

Make sure, when saving to PDF that you use the "Print" button on the "Print Preview..." window.

Related: Do you want to be able to save your inputs to a file so you can later edit them or reprint the schedule? Then the C-Value! for Windows program is what you need. It is even more flexible than this calculator, and you can save your work to a file for later recall.

Save amortization to PDF
Use Google's Chrome browser to save or print the amortization schedule to a PDF file or install PrimoPDF.

Printing the Payment Schedule

Actually, there's not a lot to say about printing...

Users should know that printing is expected to work from any device. It's pretty cool to print a well-formatted schedule from a smartphone that is connected wirelessly to a modern printer. (I've personally tested this using an iPhone 5 and iPhone X printing to an HP LaserJet Pro 400.)

Make sure you are printing from the "Print Preview..." window where there are two print buttons available.

If you have any problems, please let me know what browser and version you are using. I can test various browsers, but unfortunately, I can't check too many printers (unless you are prepared to donate one to the cause!).

Related: Don't overpay, don't under collect. If you need to track payments on the exact date they are paid (or missed) for whatever amount, then try this free online loan payoff calculator. For a step-by-step example see the payoff calculation tutorial.

What Do You Think?

Or what would you lke to know?

While this page covers a lot of material on amortization schedules, it can't cover everything.

Let me know in the comments below what I missed. Or feel free to ask your questions and I'll answer them (to the best of my ability).

Naturally, you can also tell me what I got right. Tell me what feature is particularly useful to you that you did not find in other online calculators.

MS Excel® is a registered trademark of the Microsoft Corporation.

Need More Options? Here Are 5 More Loan Schedule Calculators

613 thoughts on “amortization-schedule

  1. Hey Karl,

    Your services are being requested. My name is William, I’m a local real estate wholesaler in Cincinnati, Ohio. Recently, I’ve been buying homes “subject to” financing (owner financing, seller financing) and reselling the properties on land contracts (seller financed). I collect a non-refundable down payment, I collect monthly payments, and I amortize the balance over 30 years with interest. I would like to print an amortized payment schedule for my buyers.

    I like the amortization schedule cause it allow me to set the date back to when I initially originated the loan with my client. However, the problem I’m having is when I hit calculate I’m having negative numbers in schedule and on the last page of the schedule.

    I would like to request several things so I can learn and resolve these issues. 1.) Email me at mr.realestate01@hotmail.com so I can send you a screen shot of exactly what I’m referring to. Then, have you reply on this site. 2.) Do you have Youtube tutorials that visibility illustrate how to use everything on this site? If so, what’s your youtube channel? If not, please strongly consider making a youtube channel. 3.) Do you have a paypal or gofundme account, so I can contribute a small token of appreciation for your time?

    HouseMan Willie

    • Hi Willie,

      The email address can be found on this contact page. You’ll have to scroll down a bit. I won’t put the address here because screen scrappers will just add it to spam lists.

      Numbers will go negative when the payment does not cover the interest. One scenario when this will happen is when the time between the origination date and the first payment is longer then the regular expected periods. Such as origination date Jan 2 and first payment date Mar 21 when the normal payment period id monthly. This results in a lot of accrued interest, i.e. more than might be covered by the regular payment amount that is due on Mar. 21.

      You can send me a screen shot, but if you see that’s what’s happening, then you should be using this calculator to create an amortization schedule because under that calculator’s "Settings", you’ll find an option for "Interest" and how interest long periods are handled. Scroll down the page for a list of tutorials. I think #25 might be of particular interest to you.

      No, no YouTube channel at this time. I hope to get a few videos created this year. We’ll see.

      And regarding #3, thank you, that’s very generous, but not necessary (and I don’t have those accounts). I would much prefer that if you are happy with the site that you pass on links to your friends and associates. Or if you have a website that you can use to link back to this site as a free resource, that would really be great.

  2. What does “25 month amortization” mean

    • Where are you seeing that text? Are you asking about something you see on this calculator’s page, or are you asking about something you’ve read unrelated to this calculator and you want an explanation?

  3. I saw it as term on a proposal, wondered what it meant in the context of a 10 year contract. That’s what lead me to your page.

    • Ok, understood. I think it simply means the loan is amortized (paid off) in 25 months. It’s another way to state the term of the loan.

    • So, for a 10-year contract with monthly payments, one would say " 120-month amortization."

      • Thank-you. I was thinking that the amortization schedule for a 10-year loan would be 120 months. I didn’t understand where the 25 month amortization related to the 10-year. So it is either a typo or a different term

  4. I like your program but I haven’t found a way to print lines on the schedule. Can the program be set up to print lines on the schedule like an excel spreadsheet?
    Thanks.

    • I’m glad to hear you like the calculator. There is not an option for printing lines on the report. However, there is a work around, if you want to try it. From the "Print Preview" window, select the entire report and then copy/paste it into Excel. Once you do that, you can change the formatting and add the lines as you desired. Then you can use Excel to print. If you do that, you’ll only have to do it once. Save the workbook, and then going forward, paste the results from the print preview to the saved workbook and the formatting should remain in tact.

      Depending on your browser, you may have to use Excel’s "Paste Special" feature.

  5. Hello,

    Great site! I’m trying to set up a loan for 350,000 at 12% for a 5 year term starting May 1 with interest only the first year. Not quite sure how to come up wit that schedule. Thanks!

    • Thanks Shannon. Much appreciated.

      For what you want to do, you’ll need to use this

      financial calculator

      Scroll down the page and see tutorial #1 to get a quick overview of how the calculator works and then look at this tutorial for your specific use case:

      14 Interest Only Loan
         Initial series of interest only payments
      

      If you have any questions once you’ve check out the calculator, just ask.

  6. worthless
    I can’t print the damn thing. Even screen shot doesn’t help.

    • How did you try to print? Did you click on the "Print Preview" button and then the "Print" button in either the upper left corner of the preview window or at the end of the amortization schedule?

      If you did that, and it doesn’t print, please tell me what browser and version you are using. And if you are on Windows or what operating system.

  7. I’m using Firefox. I don’t see a print preview button. Here’s the page I was looking at. If I can print it, I take back my ill tempered remark. I thought I had to pay $69 to get a printable version. THis is a one time thing for me.

    https://financial-calculators.com/amortization-schedule

    • Nope, no need to pay $69 or anything.

      And no problem with FireFox.

      Presumably, you saw the "Calc" button? In that row, go 2 buttons to the right for "Print Preview."

      By the way, the "Print Preview&quot button also calculates the schedule, so no need to click on the "Calc" button too.

  8. These guys ROCK! I had troubles using this program, but Karl was great, helped me through it, and it worked like a champ! I was making a stupid mistake, missing something that was right in front of me!

    Peter

  9. Hello, I’m trying to figure out a schedule for one of my clients and they got behind on some of their payments (and some they paid more but are still about 11k behind). So I am wondering if there was an option to enter in what they paid so I can show them on the schedule what I owed on the balance?

    This would help out a great deal if I could personally enter in some of their payments in order to do show their personal schedule to them.

    Thank you so much for your time in this matter.

    -Adam

    • Correction:
      **What they owe on the balance.

      • They started on a 175,000 note with 11,000 down and me financing the rest over a 15 year term at 7% interest. I charge $50 late fee if not paid by the due date (I didn’t see a late fee column as well). Just trying to figure this out, thank you again for all your help in this matter.

        -Adam

        • Sorry just trying to give all information you may need:

          They started Aug. 11 2016, with their first monthly payment starting Oct. 1 2016.

          -Adam

          • Hi Adam, you can do what you want, but just not with this calculator.

            Please use the Ultimate Financial Calculator. That calculator is designed to allow the user to put in each payment as it is made. The user can also put in a series of payments if some of them were regular, i.e. paid on the date due.

            If you try it, scroll down the page to the tutorials. Everyone should review tutorial #1. Then tutorial #25 addresses your specific needs:

              25. Calculate Loan Balance — Loan Payoff Calculation
                  Enter payments for any amount on date made — audit balance due
            
  10. Hi,
    Could it be that this site has changed?
    I am trying to calculate an amortization schedule showing straight line amortization, not one which shifts around. I expect to see that the principal portion of the payment will increase steadily, and the interest portion will decrease steadily. I have been able to generate this in the past, but perhaps I am not following the same settings or something. Can you please help me?

    loan $48,000
    interest rate 9.5%
    15-year, 180 month term
    $512 monthly payment

    Thank you

    • Hi Janice, this calculator has not had any changes in over a year. You should see an increasing amount being allocated to the principal with each payment made.

      There are conditions, however, when this does not happen. If the compounding is set to continuous, daily or exact, some payment will have less applied to principal than the immediately preceding payment due to the difference in the number of days in the month.

      Or if the first period is a longer or shorter period than the following regular length periods, the principal will change.

      If this does not answer your question, then I need to see your schedule to understand the specifics.

      • Karl,
        This answers my questions perfectly. Thank you for your complete and speedy reply. I changed my specs to “monthly” compounding, and all is as I had expected — straight line amortization (if this is what it is known as.)

        Thanks!
        Janice

        • Great. Thanks for letting me know. And regarding, "straight line amortization", you may have just coined a phrase there. 🙂

  11. HI THERE!
    I need an amortization schedule with no interest 48 month loan with $50 month late fee… thanks!

    • Hey back.

      Is this a question? Are are you saying how you are using this calculator?

      If it’s a question, under the "Amortization Method" setting, there is a "No Interest" option. You have to use this setting, because if you don’t, setting the interest rate to 0, causes the calculator to think the interest rate is unknown.

  12. I tried that but there was no way to figure in late fees for missed or late payments

  13. I’D LIKE TO DO THE SAVE BUTTON, BUT DON’T HAVE A PAYPAL ACCOUNT NOR DO I WANT ONE – THERE IS A ONE AND DONE WAY TO USE PAYPAL, SEND MONEY FOR SERVICES, CAN I DO THAT?
    THANKS!

    • Mastercard, VISA or American Express are the payment options.

      Also, before purchasing, make sure the calculator will do what you want. From your comment about late fees, you should be using this financial calculator.

      With this calculator, a late fee is added as a new loan amount. It is not marked "late fee". Scroll down the page and see tutorial #25.

  14. Hi Carl,
    How can i download the excel file? i need it onward calculation into budget reports. Going to print preview and copy paste from their wont allow to have the excel formula.

    • Hi Rizwan, this calculator does not generate an Excel file. Copy/paste is the only way to get the data into Excel. Even if one could download and save the schedule to an Excel file, that doesn’t mean the equations would be available.

  15. Hello Karl,
    Is it possible that the calculator under (https://financial-calculators.com/amortization-schedule) might not be calculating the payment amount correctly when using week-based compounding? (e.g. Weekly, Biweekly, Every 4 weeks)
    I tested this using the following data: Loan = $32,500; APR = 7.5%; Payments # = 8; Loan Date = 07/01/2018; First Payment Due: 08/01/2018; Payment Frequency: Monthly; Compounding: Weekly; Points: 0%; Amortization Method: Normal.

    Using these variables your calculator computes a Payment Amount of: $4,179.16

    I used PMT function in Excel for calculating annuities.
    I applied the following formula for calculating the period interest rate (i) = (1+R/N)^(N*(1/T))-1
    R = 7.5%, N = 52 (weeks in year); T = 12 (for months in year)
    i calculated = 0.006265041

    (The formula above is an adjusted version of the basic formula for compounding interest (i) = (1+R/N)^(N*T)-1; In my formula I invert T to 1/T to enable calculation of period interest for weekly or monthly loan installments.)

    For PMT I used the following data: PV = $32,500; Rate = i (above); Nper = 8; FV = 0; Type = 0.

    Using these variables results in PMT = $4,177.87, a difference of $1.29

    I am not really well versed in mathematics, so it is possible that I am using an incorrect formula (or a correct formula incorrectly).

    Interestingly, when I apply my formula above to month-based compounding, Excel (PMT) will in ALL cases compute exactly the same results as your calculator does. On the other hand, in the case of week-based compounding ALL cases for Excel (PMT) result in differences with your calculator.

    I would be most obliged if you could let me have your thoughts on this.

    Kind regards,
    Mark

    • Hi Mark, first, as an aside, the calculated payment amount isn’t all that important. If you want to use $4,177.87, this calculator will allow you to do so. The only difference will be the principal won’t be paid back as quickly. Or that should be the only difference.

      As to the $4,179.16 payment this calculator calculates, if you look at the end of the schedule (assuming a 360 day year) there is only a $0.04 rounding amount. Thus if the payment is increased or lower by even a penny, the rounding will be greater than 4 cents.

      Thus $4,179.16 is the most “accurate” amount.

      But here’s the thing, while the calculated payment amount is not particularly important (so long as the lender and borrower agree to the amount), what IS important is the interest calculation. After all, the interest is the cost of the loan. This is where it gets somewhat complex because of the monthly payment and weekly compounding. Take the first period, July 1 – August 1. Its 4 compounding periods plus 3 odd days. That’s the amount you want to confirm, in my opinion.

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