This compound interest calculator calculates interest between any two dates. A dozen compounding frequencies are supported (did we miss any? :). You can also enter negative interest rates. More details below
When interest is compounded, interest is paid on previously earned interest. If you are an investor, you want to compound interest. If you are a debtor, you want to avoid it, particularly if you ever miss a payment or a payment is not enough to cover the interest due.
You can use this online interest calculator as a:
- loan interest calculator
- savings interest calculator
- daily interest calculator
- negative interest calculator
- investment interest calculator
As a side benefit to this calculator's date accuracy, you can use it for date math calculations. That is, given two dates, it will calculate the number of days between them or it will find the date that is "X" days from the first date.
Compound Interest Calculator Help
Enter an amount and a nominal annual interest rate.
Date Math: If you change either date, days between dates will be calculated. If you enter a positive number of days, the end date will be updated. If you enter a negative number of days the start date will be updated.
The above means you can calculate interest for a specific number of days and not worry about what the dates are. If you need to know the interest for 31 days, then enter 31 for the number of days and don't worry about the dates.
Set the compounding and days-in-year. Click "Calc". Interest and future value are calculated (FV is starting amount plus the interest.) Annual percentage yield is used for comparing investments. It is the rate institutions must quote in the US for interest bearing accounts. The holder of such an account can use the APY to compare different accounts.
Interest may be calculated based on a unit of time, say a month. This is known as "Periodic Interest" In that case, a month's interest is always the same for the same interest rate and same principal balance regardless of the length of the month. Given $10,000 principal and an interest rate of 6.75% the interest will be the same for February as it is for March. Note if you select a periodic method such as "weekly", "biweekly" etc., and if the dates enter do not equate to a number of full periods, then interest will be calculated for the fractional period by counting the days and calculating simple interest. This generally results in 1/2 a month's interest being less than 1/2 of a full month's interest when using monthly compounding.
There is also "exact day interest". Interest is calculated based on the number of days. In this case, the amount of interest will be different for February and March. Set compounding to "continuous", "daily" or "simple" for daily interest calculations.