Compound Interest Calculator
Project how savings or investments grow with compounding.
The power of compounding
Compound interest pays interest on your interest. The formula is A = P(1+r/n)nt, plus the future value of any regular contributions. Small, consistent monthly deposits usually matter more than the starting amount — try it above.
Choosing the inputs
For long-term stock-market projections, many planners test 5–8% annual returns; for savings accounts use the advertised APY. Compounding frequency (monthly vs yearly) makes a modest but real difference over long periods.
Frequently asked questions
What is a realistic rate to enter?
Use the actual APY for savings accounts. For diversified investments, run conservative and optimistic scenarios rather than a single number.
Does this account for inflation?
No — results are nominal. Subtract expected inflation (historically around 2–3%) from your rate to see real purchasing power.