Compound Interest Calculator

How to use Compound Interest Calculator

Enter the initial balance, annual nominal rate, duration and end-of-month contribution. The calculator applies the annual rate divided by 12 for each monthly period.

How Compound Interest Calculator calculates the result

Each monthly period starts with the previous balance, adds monthly interest at annual nominal rate ÷ 12, then adds the monthly contribution. Repeat for the chosen number of months. Actual investment returns are rarely constant.

Example

Starting with 1,000 and contributing 100 per month means total contributions are 13,000 after ten years, before any compounding growth.

What to know

Assumes a constant nominal rate and monthly compounding. Does not model taxes, inflation, market volatility, fees or intra-month deposits.