Compound Interest Calculator Free
See exactly how an investment or savings amount grows over time with compound interest.
How to use this tool
- 1Enter the principal amount.
- 2Enter the annual interest rate.
- 3Enter the time period in years.
- 4Select the compounding frequency — yearly, quarterly or monthly.
About this tool
Compound interest grows non-linearly, which makes it almost impossible to estimate mentally once the time period stretches past a few years. The same rate compounded monthly rather than annually produces a visibly different figure, and that gap widens the longer the money sits. This calculator takes principal, rate, term and compounding frequency and shows the final amount alongside the total interest earned, so you can compare a fixed deposit against a savings account, or check whether a longer lock-in genuinely pays for the loss of access. It also makes the reverse case clear: the same maths is what makes carried debt expensive, since interest on an unpaid balance compounds in exactly the same direction.
Frequently Asked Questions
What's the difference between simple and compound interest?
+
Simple interest is calculated only on the principal; compound interest is calculated on the principal plus previously earned interest.
Which compounding frequency should I choose?
+
Match it to your actual account terms — monthly and quarterly are the most common for savings accounts and deposits.
Does it account for inflation?
+
No. The result is a nominal figure; subtract your expected inflation rate for a real-terms view.