This simple interest calculator calculates interest between any two dates. Per Dictionary.com simple interest is "interest payable only on the principal". Interest is never earned or collected on previous interest. More below...»
Simple interest is the interest calculation method that is least beneficial to savers and the most beneficial to borrowers. But note, if payments on a debt are paid as frequently as the compounding and the payment covers the interest due, then even if the terms of the loan call for compounding, there will be no impact on the total amount paid because at no point will there be any unpaid interest.
When the terms of a debt call for a simple interest calculation, if a payment does not cover the interest due, the unpaid interest must be tracked separately from the unpaid principal balance (also known as the US Rule). We believe that our Time Value of Money Calculator is the only online financial calculator that gives users this option and creates a schedule that shows the unpaid interest balance.
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 accounts.
Interest is calculated based on the number of days. In this case, the amount of interest will be different for February and March.
This site also has a "Compound Interest Calculator"