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Why do people pay an "extra" amount when paying back a loan?

They do it to reduce the loan's interest charges, and to pay off the debt earlier.

If I make extra payments, how much will I save?

When will the loan be paid off?

The answer to both questions depends on the current balance, the loan's interest rate, when you start making extra payments, and the additional payment amount.

In some cases, usually for longer-term loans such as mortgages, the savings in interest charges can be quite substantial. If the borrower starts making the extra payments early enough, and for an amount that's not exceptionally large, it is possible to save tens of thousands of dollars on a $200,000 mortgage (the average size new mortgage balance as of 2017, according to the Consumer Financial Protection Bureau was $260,386).

Specifically, with an average mortgage, by making $200 a month extra payments, the borrower will save over $50,000 assuming a 30-year loan and a 4.25% interest rate.

How is this possible? What sleight of hand is taking place?

There's no sleight of hand. The future savings are a mathematical certainty. It all has to do with the way loans, and mortgages work. The periodic interest amount is calculated using the loan's current balance and multiplying it by the periodic interest rate - the lower the balance, the lower the interest amount due.

Thus when you prepay principal (make extra payments), you are lowering the loan balance used for calculating the interest due.

As I said, this is a mathematical certainty, and this calculator will show you just how much interest you'll save on any loan, and when the loan will be paid off.



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Click, copy, paste this URL to save the inputs for yourself or to share with others.

This custom URL updates when you click the "Calc", "Clear" or "Schedule" buttons. Paste it into a browser's address bar to reload.

Sounds pretty good, right?

Of course it does!

But, what if I told you, "How much will I save if I make extra principal payments?", isn't the question you should be asking?

"What If I Invested the Money Rather than Make Extra Payments?"

Ahh, that's the more important question!

Rather than reducing interest costs via prepaying principal, what if you saved and invested the money? Would you be further ahead?

That's that critical question to be asking.

If you have $200 and you use it to make a prepayment toward a loan, you can't also use the same $200 for investing. Economists say, not being able to invest is a foregone opportunity. The opportunity to do something else with that same $200 won't come back. The chance is gone.

How then do you know which is the better decision?


Use this calculator!

The calculator uses "Your Investment Rate-of-Return," and calculates the future value of all the projected extra payments. It then calculates the investment gain and subtracts it from the "Total Interest Saved" to arrive at the net gain from the extra payments (the "Interest Saved Less Investment Gain" shown).

Let's look at an example.

When you come to this page, you'll find the calculator preloaded with a $260,386 loan/mortgage, and $200 a month is the default prepayment amount.

For the investment rate-of-return, the calculator uses as a default 7.2%, which is the approximate average rate-of-return for the S&P 500 according to this (somewhat dated) analysis. (Dated, yes. But considering what the stock market has done since this study, my 7% assumption for deciding whether or not to make extra payments on a loan is conservative.)

You, of course, are free to use whatever rate-of-return you like.

Using these defaults, here are the results:

Savings from making extra payments
Extra payment calculator results. In this case, investing is more advantageous.

$52,829 in interest savings and the mortgage that would have usually taken 360 payments to pay off, will be paid off after 276 payments.

But, here's the real story.

If the borrower takes the $200 a month and invests it, after the 276 months, their investment GAIN will be $81,238! (Total value of the investment account will be $55,000 in extra payments invested plus the $81,238 gain equals $136,238.)

Now it should be apparent that while a $52,000 savings is terrific, an $81,000 gain is better.

Just how much better?

$28,409 better, as the final result "Interest Saved less Investment Gain" ($52,929 - $81,239) shows you.

If, after plugging in your numbers, you get a negative result too, then YOU SHOULD CONSIDER NOT MAKING EXTRA PAYMENTS!. You'll, at least hypothetically make more money from your investments than you save in interest charges.

Want to confirm the results?

Then make sure you click on the "Supporting Schedules" button. There you'll find all the supporting number that went into the above analysis. There's a detail amortization schedule showing the periodic payment and interest charges as well as the extra payments coming off the principal balance.

After the loan payment schedule, you'll find a future value or investment schedule. This schedule documents the capital gain from the invested extra payments.

Amortization schedule with extra payments
The amortization schedule with extra payments followed by the investment schedule

When might you want to continue to make extra principal payments even when the calculator indicates investing might be the more prudent course to follow?

There are at least two reasons I can think of when you might not want to invest the prepayment funds.

I can express one reason with a single word - Risk!

Remember when I was discussing why making prepaid principal payments saves the borrower money, I used the phrase "mathematical certainty?" If the borrower makes the extra payments as anticipated, then the interest savings is a sure thing. The lender can only charge the periodic interest on the outstanding balance of the loan.

But, if you invest, and even if you invest per the anticipated schedule, for the full amount and on the scheduled day, the return on the investment is likely not to be guaranteed (though true, some investment instruments might offer a guaranteed profit). In that case, at the end of the term, when the loan would have been paid off, you might not have the capital gains that you had anticipated. Of course, you might also have a more significant gain than what you had anticipated.

That's the risk.

The second reason why you might not want to invest is that you want to live debt free. I understand how when someone takes out a 30-year mortgage, they might dream of living without any mortgage debt in say 20 years. I get that. The fact is, that's how I felt, and that's what I did - but I did it before I created this calculator!

For here's the thing. It is possible to be both free of debt early and to implement an investment strategy for your funds rather than a principal prepayment strategy. They are not mutually exclusive!

Let me walk you through this, step-by-step:

Debt free date with extra payments
Debt free date with extra payments.
Balance on debt free date
You'll have a $92,929 loan balance on the debt free date when no extra payments are made.
Investment account's value as of debt free date
But there's over $136,000 in the investment account as of debt free date. You can still pay off the loan!
  1. Look at our example again - the one the calculator preloads when you first come to this page (click on your browser's refresh button if you want it back). At the time of this writing, the analysis shows the final payment scheduled for March 1, 2042. Make a note - that's the debt-free date with extra payments.
  2. Now set the extra payments to 0 and look at the schedule. This is the schedule without any additional payments. Find the balance as of the debt-free date. Again, as of this writing (these illustrations are time sensitive), the balance will be $92,929.
  3. Now, one more time, reenter the extra $200 payment amount and recheck the investment schedule located after the loan schedule. (The calculator prepares an investment schedule only if you have entered an extra payment amount AND if the option "Include the Investment Schedule?:" is set to "Yes.")
    • As shown, when making prepaid principal payments, the loan is paid off in 276 payments - or 23 years.
    • On March 1, 2042, the balance in the investment account will be $136,238.
    • You can easily pay off the mortgage using the funds in the investment account, live debt free as of the date planned, and still have nearly $40,000 remaining!

Of course, there is a rub.

This analysis overlooks the impact of taxes. If you live in the US, all or part of the interest may be deductible from your income taxes (though after the 2017 tax law changes, this is not as much of a certainty as it had been in the past). One the investment side, income taxes will frequently have to be paid on any investment gain, thus reducing the illustrated gain.

But even taxes on the gain are not a foregone conclusion. If you were to invest in tax-free bonds, then there is no tax on the income (but the illustration probably won't be as favorable). Or if you invest and don't sell along the way, the gain will compound tax-free. You'll only pay income taxes on the gain when you sell. And generally, income taxes on long term capital gains are very favorable to investors.

No doubt these points about taxes are something you need to consider. If I were to program the various tax considerations as options for this calculator, I think it would leave users very frustrated - not to mention me!

The Calculator's Features

Of course, your situation is likely different than this hypothetical example. So you'll want to use this Extra Payment Calculator to see just what you can save and when your loans will be paid off.

Let me take a few moments to go over some the other features this calculator supports.

If you don't plan to make extra payments monthly, that's okay. The calculator will let you make additional payments using any one of 11 payment frequencies set independently from when the scheduled payments are due.

For example, do you get an annual bonus? Do you want to use that bonus to prepay principal? This calculator will still calculate your saving under such a scenario. You can easily set it to make one or two extra payments a year.

Or do you want to make a one-time extra payment? That's no problem either. The calculator supports making a single extra payment on any date during the term of the loan. Perhaps you've received a one-time inheritance, and you are considering using it to reduce your loan's principal balance. The Extra Payment Calculator will tell you the amount of interest you'll save and when the pay off will be.

Don't forget to check out the amortization schedule for all the details.

(Perhaps I should also point out that the loan itself does not need to follow a monthly payment schedule. The last option on the Extra Payment tab allows the user to select any payment frequency.)

This Calculator is Not Just for New Loans.


Up until now, I've been implying that the calculator is only for analyzing new loans. That's not the case. Perhaps you've been making loan payments for a few years, and you've recently received a raise. If you want to see the impact of making extra payments on an existing loan then there are no unknowns for the calculator to calculate (other than the effect of making the prepaid principal payments of course), so enter the following for the first four inputs:

  • The loan's balance as of the last payment due date.
  • The number of payments remaining.
  • The loan's interest rate.
  • The regular payment amount.

The calculator will use the terms of your loan for the analysis.

There is also one other setting to be aware of. On the "Extra Payments/Investment Rate" tab, please see "Is a Regular Payment Due Today?:" This setting impacts the analysis. It is set to "No" by default. However, if for the loan balance, you enter the balance as of the date a payment is due, then you should set this to "Yes." This prevents the calculator from adding the accrued interest since the last payment due date.

If you don't follow the above, please don't stress out. It won't make that big of a difference!

Don't Forget the Charts

No doubt if you spend time going over the schedules, you may find your eyes glazing over. (For sure, there are a lot of numbers!) If you find that happening to you, or if you aren't a detailed "numbers person," make sure you check out the nine charts that the calculator automatically creates.

Chart showing extra principal payments
Top chart showing extra principal payments. Bottom chart showing investment gain.
  • Annual Totals without Extra Payments
  • Annual Totals with Extra Payments
  • Annual Investment Plus the Annual Gain
  • Accumulated Totals without Extra Payments - running totals since the loan's origination
  • Accumulated Totals with Extra Payments
  • Accumulated Investments Plus the Total Gain - show year-over-year growth and final value
  • Pie Chart Loan Payment Total Allocated to Principal and Interest
  • Pie Chart Loan Payment Total Allocated to Principal and Interest with Extra Payments
  • Pie Chart Showing Breakout of Investments and the Gain on the Investments

Wrapping Up

When you were searching for an extra payment calculator, you probably just wanted to see how much interest you could save. You didn't expect there to be so many things to consider.

Don't feel as if you need to digest all of this in one sitting. Come back and try different scenarios. Make different assumptions.

But remember, the point is, no matter what decision you make, the calculator will help you to make an informed one.

You can let me know in the comments below.

95 Comments on “Extra Payment Calculator”

financial online calculator Join the conversation. Tell me what you think.
    • There is no export to Excel feature, but you can select the entire payment schedule and then copy/paste it to Excel. But note, depending on what browser you are using, you may have to use Excel’s "Paste Special" feature.

      About a year ago, I did look into adding an export to Excel feature, but it’s not clear to me what users expect when they ask about this. Is it just the data they are interested in loading in Excel? Or do they expect the schedule to be nicely formatted? Or do they expect the equations? I can imagine several different use cases.

  • My vehicle loan lender says they are using the “True Daily Earning Method” to determine my loan parameters. The particulars are as follows:
    Loan Amount: $14,435.69
    Annual Percentage Rate: 23.5115%
    99 Semi-Monthly Payments: $227.70
    First Payment Paid 6-25-18.
    (Interest $86.95
    Principal $131.28
    Towards Sales Tax $9.47)

    I paid an extra $100.00 towards the principal of which they said $95.84 went to principal and $4.16 must go towards sales tax.

    I intend to pay an extra $100.00 ($95.84) to the principal every payment and want to know how much of an effect this will have on shortening the length of the loan and how much interest I will save?
    How and what calculator do I use to figure this?

    • Does the loan amount of $14,435.69 include the sales tax owed or is the sales tax added to the loan balance?

      What is the sales tax rate (percentage)?

      As of now, I think this calculator should do it for you. Did you have any questions about how to use it?

      • My question is similar.

        I would like to calculate the affect of an extra annual payment of 2500 on an auto loan. It seems all the calculators figure a monthly extra payment. Is there a way to change the frequency of the extra payments?

        I am trying to figure how to create these calculators, because all of the calculators that exist which feature the option to change the extra payment frequency use mortgage amortization.

        • You’ll need to use this calculator. It will allow you to enter extra payments using any frequency.

          If you try it, scroll down the page to the tutorial section. There are 25 tutorials – 2 deal specifically with extra payments. Also, check out tut #1 for an overview.

  • I really appreciate this calculator. I use it regularly to plan my mortgage pre-payments. It obviously doesn’t calculate everything everyone wants, but I find it extremely useful.

  • I wish there was a way to put my total mortgage payment in, including escrow payments, so I can see how much extra I truly need to pay to get my mortgage paid off in 10 years!

    • Two things.

      First, the escrow portion of the mortgage payment has no impact on when the mortgage is paid off. You don’t even have to think about it, because when the mortgage is paid off and goes away, you’ll still have to pay the escrow – usually property taxes and insurance. If you want to see what your total payment will be and still pay the loan off in 10 years, use this calculator and then add the escrow amount to the payment it suggests to reach your goal of being mortgage free in 10 years.

      That said though, you can use this mortgage calculator and it will consider the various items that go into escrow as well as extra payments on the mortgage amount.

      If you try it, and have questions, just ask.


    Hello Karl
    Thank you for trying to assist. i’m done, unable to get it correct.
    It can not be this complicated, there must be a reason I do not understand.
    It is what it is!
    Zero struggles with other calculators. I’m done!

    Dolf sr

    • Understood. Thanks for stopping by.

      I just noticed you are writing from a different calculator page. The instructions I had given you before were for a different calculator, so perhaps that caused some confusion.

      Also, in our few exchanges, you never said what you are trying to accomplish. That would have help, along with the specifics, of course.

  • Dolf vanKesteren says:

    Hello Karl,
    All I was trying to accomplish was put a loan summary together, showing:

    loan amount, payments, interest, principal and additional monthly payments.

    how difficult an this become?

    1st issue was date, you fixed that for me, I was able to download one time
    a loan summary, pretty accurate. 2nd time NO WAY, THIRD TIME NO WAY.

    inconsistency’s every time so I gave up. 1st time used different calculator from
    other company, issues resolved. Why not allow consumer to contact you by phone
    this would make things a lot easier.

    I do appreciate you continue to take care of this issue, however, how many times

    do we have to go over the same thing? I feel strongly that there is a issue with

    the program, software. I do make mistakes, however over and over again???? give me a break.

    Dolf sr

    • Understood. Should you ever want to try the mortgage calculator again, this is all you have to do to get a "loan summary."

      1. Click the "Clear" button – to reset all options and the inputs to 0
      2. Enter the "Loan Amount"
      3. Enter the "Number of Payments" expected per terms of the loan
      4. Enter the "Annual Interest Rate"
      5. Leave the principal and interest "Payment Amount" set to "0" for the calculator to calculate or enter your own payment amount if you wish.
      6. Click the "Payment Schedule" button and you’ll be looking at your "loan summary" (without extra payment yet)

      That’s it. Nothing more. You don’t have to touch any other setting or option. The calculator will give you consistent results if you do the same thing.

      Now, if you want to see the impact of making extra payments, do this:

      1. Click on the "Options" tab at the top
      2. Enter the "Extra Payment Amount"
      3. Enter the approx. date for when "Extra Payments Start"
      4. Set the "Extra Payment Frequency" – how often do you expect to make them. You can make them more or less frequently than the normal principal and interest payments.
      5. Enter the "Number of Extra Pmts" you expect to make. This can be simply "1" if you wish. Or it can be "Unknown" if you want ot make the extra payments until the loan is paid off.
      6. Go back to the "Calculator" tab and click "Payment Schedule" button again and you’ll be looking at your schedule, this time, with the extra payments included

      Again, no other setting needs to be changed.

      Much of this is outlined right below the calculator in the section "The Mortgage Payment".

      If you start changing the dates, that will most certainly start changing your results. And perhaps you’ll view things as not being consistent. Please see the section "ABOUT DATES," in red, a little further down the page. (Date change definitely impact interest calculations and this calculator reflects that fact. It is sensitive to a change in a single day. Not many calculators on the internet are.)

      One other point, if the loan isn’t really a mortgage, but just a more "normal loan" or you’re not interested in working from the "Price of Real Estate or Asset" or including PMI etc, then I suggest you try the more basic loan calculator on this site. It has the same options for extra payments, but a lot few settings. You should still understand about dates and how they impact interest calculations and the options available to the user for when and how interest is collected.

      But if you keep the loan date and the first payment date always one month apart, (assuming monthly payments), then you should not really have any issues with interest calculations.

  • Hi, My extra payments vary each month. Is there a schedule you have where I can type in each monthly payment to get my balance?

    • Hi Karen, yes there is. Please use the Ultimate Financial Calculator.

      This calculator is designed to allow you to enter each payment on the day it was paid – whether the payment is a regular payment or an extra payment.

      Once on the page, scroll down, and you’ll see some tutorial. Two deal with extra payments and #25 is about tracking payments. You should probably review #1 to get started.

  • Am I missing something? I’m entering extra payments made weekly, but it does not calculate them as if made weekly; rather, it takes the payment amount and makes it monthly. That is, when I try to run calculations of making $25/week extra or $100/month extra to compare, the $25/week calculation only makes the payment monthly. It is as if the frequency variable isn’t working.

    • I’m not having that problem. Perhaps there’s a bug if the steps are not executed in the same way I’m testing it.

      Without changing anything, I click on the "Extra Payments/Investment Rate" and set the "Extra Payment Frequency" and set it to weekly to start on Sept. 15, and then I click on "Calculator" and the "Supporting Schedules" button.

      I see weekly "XPmts" for $25.00.

      Did you do other steps by any chance (beside change the loan details)? Maybe some step is not getting reset properly. If you still have the problem and can give me the details so that I can duplicate it, I can then fix it.

  • Michael Carrozza says:

    Absolutely fantastic calculator! Thank you for your time and effort in creating it.

    I currently have 5 student loans with varied balances, interest rates, monthly payments, and number of payments remaining. I’m trying to determine how extra payments can most efficiently help me payoff all loans (1) in the shortest amount of time and/or (2) with the most saved in interest. I plan to begin with a fixed amount per month (e.g., $250), then add to that amount the monthly payment for each loan once it is paid off.

    For example, suppose loan A has a balance of $8,000 at 7.25% with 150 payments remaining, and loan B has a balance of $25,000 at 7.75% with 90 payments remaining. Am I better off paying $250 extra per month towards loan A, then add that monthly payment to $250 as extra per month towards the remainder of loan B, or vice versa?

    As I said, I have 5 loans, so while I can manually do the calculations in the two-loan example above, the math is too complex for five loans.

    Do you have a calculator that can do that? Or, is it possible to use this calculator to determine this?

    Many thanks!

  • I want a calculator where I can modify the monthly payments over the next 3 years showing increased payment to determine when my home is paid off earlier. How can I do this?

  • Thank you so much for this calculator! I was about to input different scenarios to see what would give the best outcome. I went with the extra lump payment yearly instead of the extra money payments even though the savings were extremely close. I wish I knew more about investing but I really don’t so I didn’t even consider investing the additional principal payment. My goal is to learn more about investing and hopefully by the next lump payment I will be able to compare both scenarios.

    Thank you Karl!

    • Thanks for your comment Ro, and for letting me know how you are using the calculator.

      Just take it one step at a time. Calculators can be very useful as a teaching tool.

  • I think the 30 years fixed mortgage’s amortization table is fixed. Unless you do a recast. That is the interests pay each month is fixed. Extra payment goes to principle but not saving interests each month. You save the interests by paying off early at the end. Now, why should I lock my extra money in the mortgage instead of investing somewhere else? I can achieve the same saving by paying off the loan early by a lump sum at the end. Basically my question is down to: does the amortization table recalculate each month on a 30 years fixed mortgage? Only if it does, then makes sense to pay more each month since interests will be reduced by the reduced principle. Thanks.

    • When you use the term "fixed", I assume you are using it in the sense of a traditional 30-year, "fixed-rate" mortgage and not "fixed-principal" loan.

      The key takeaway here is "fixed-rate", not "fixed-amount". The interest paid each month is NOT fixed. The interest is calculated using the loan’s current balance. So when one prepays the principal, the balance is lower, and the interest is lower than it would otherwise have been. So the interest savings come immediately and not just at the end of the loan, as you suggested.

      Study the schedule this calculator creates. Compare a loan with no extra payments to one with even just one extra payment and you should see what I mean.

      • Thanks. Yes that’s what I meant of fixed. So you are saying the amortization table does get recalculate each month, right? Not just on arm loans but also 30 years fixed mortgages.

        • Yes.

          But I wouldn’t think of it really as being "recalculated." Anytime someone borrows money and they are given an amortization schedule, they are being given a projection. If the payments are always paid on the dates indicated, then at the end of the loan, that’s what they will have paid. But vary just one payment, by as much as one day, and the initial schedule will not be precise. Whenever a payment is paid, the lender will calculate how much of the payment is allocated to interest using the loan’s current principal balance, the days since the last payment, and the (fixed or current adjustable) interest rate.

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