How monthly compounding works

The calculator divides the entered nominal annual rate by 12. Each month, the existing balance grows by that monthly rate. Contributions are treated as equal deposits made at the end of each month.

Contributions and estimated growth

Total contributions equal the initial amount plus every monthly deposit. Estimated growth is the ending balance minus those contributions. At a zero rate, the ending balance is simply the sum contributed.

Important assumptions

The rate remains constant, every contribution arrives on schedule, and there are no taxes, fees, withdrawals, inflation, or market losses. Actual investment returns vary and can be negative; a quoted savings yield may also use a different compounding or annual percentage yield convention.

Choose the tool that matches the quoted rate

Use the High-Yield Savings Calculator when a deposit account publishes APY. Use the Investment Return Calculator to measure gain from beginning and ending values instead of projecting a future rate. The APR, APY, and interest-rate guide explains why those inputs cannot be substituted without changing the result.

This educational projection is not financial or investment advice and does not promise a return. Verify product terms and consider qualified advice for important decisions.