Compound Interest Calculator
See how your savings or investment grows with compound interest over time.
Compound interest is often called the most powerful force in personal finance — your interest starts earning its own interest, and over long time horizons the growth curve steepens dramatically. See exactly how your savings or investment grows.
Why compounding frequency matters
The more often interest compounds — daily vs. monthly vs. annually — the faster your balance grows, though the difference shrinks as the frequency increases (daily vs. monthly compounding is a small difference; annually vs. monthly is bigger). Most savings accounts and investment accounts compound daily or monthly.
Time matters more than rate in the long run
Because compounding is exponential, starting early has an outsized effect. $5,000 invested at 7% for 30 years grows to roughly $38,000 — but the same $5,000 invested for just 20 years only reaches about $19,300. Ten extra years roughly doubled the outcome, more than a couple extra percentage points of return would have.
Frequently asked questions
What's the difference between compound interest and simple interest?
Simple interest is calculated only on your original principal every period. Compound interest is calculated on your principal plus all previously earned interest, so your growth accelerates over time. See our Simple Interest Calculator to compare the two directly.
Does this account for regular contributions, like monthly deposits?
No — this calculates growth on a single lump sum. For an account where you're adding money regularly, use our Savings Calculator or Retirement Savings Calculator, which factor in periodic contributions.