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Compound Interest Calculator

See how your investment or loan balance grows over time with compound interest. Works for both savings and debts.

Principal or starting balance
Enter as percentage, e.g. 5 for 5%
Number of years money is invested or loan term
How often interest is compounded
Extra deposit (investment) or fixed monthly payment (loan). Use 0 if none.
Future balance $2,801.92
Total principal contributed $2,000.00
Total interest earned / charged $801.92
Principal Interest

How compound interest works

Compound interest is the process where interest is earned on both the initial principal and the accumulated interest from previous periods. This tool is a reliable compound interest calculator that lets you estimate future value for savings, investments, or loan balances. Whether you're using it as an investment calculator to project growth or as a loan interest calculator to understand total debt, the math behind it stays the same: the more frequently interest compounds, the faster the balance grows (or accumulates).

For investments, adding regular monthly contributions can dramatically boost your ending balance thanks to dollar‑cost averaging and extra compounding. For loans, the same formula works in reverse: interest accrues on unpaid balances, and if you only make minimum payments, compounding can increase the total cost significantly. Play with the numbers to see how small changes in rate, time, or contributions affect your outcome.

Use this compound interest calculator to compare different scenarios — adjust the rate, compounding frequency, or monthly payment. It’s a practical tool for planning retirement, saving for a goal, or evaluating the true cost of a loan. Remember, past performance doesn't guarantee future results, but understanding compounding helps you make informed financial decisions.