Project how your money grows with compound interest and regular contributions — with a year-by-year table and an optional inflation adjustment.
Year by year
| Year | Contributed | Interest that year | Balance | Today’s money |
|---|
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How to use the Compound Interest Calculator
- Enter your starting amount, the annual interest rate and how many years to project.
- Add a regular contribution and choose how often interest compounds (monthly is typical for savings accounts; daily for many banks).
- Turn on the inflation toggle to see what the final balance is worth in today’s money. Scroll down for the year-by-year table.
About this tool
Compound interest means you earn interest on your interest. The basic formula for a lump sum is A = P × (1 + r/n)n×t, where P is the principal, r the annual rate, n the number of compounding periods per year and t the years. Regular contributions add a second term: each deposit compounds from the date it’s made.
The calculator steps through the projection month by month, converting your compounding frequency to an equivalent monthly rate, so daily, monthly, quarterly and annual compounding are all handled exactly. With inflation on, it also shows the real value — what that future balance would buy at today’s prices — which is the figure to use for retirement planning.
Frequently asked questions
How much difference does compounding frequency make?
Less than most people expect. At 5%, 10,000 becomes 16,289 with annual compounding and 16,487 with daily compounding after 10 years — about 1.2% more. The rate and the time matter far more.
What’s the rule of 72?
A quick estimate: divide 72 by the interest rate to get the years it takes money to double. At 6% that’s about 12 years; at 9% about 8 years.
Why show inflation-adjusted values?
Because a balance in 30 years buys less than the same amount today. At 3% inflation, prices roughly double every 24 years, so a nominal 1,000,000 then is worth about 400,000 in today’s money.
Are contributions made at the start or end of each month?
End of month. Contributing at the start earns one extra month of interest on each deposit — a small difference over long periods.