Compound Interest Calculator
See how an investment grows over time with compounding and regular contributions.
Leave at 0 for a one-off lump sum.
Future value
$24,540.94
Total invested
$10,000.00
Interest earned
$14,540.94
With simple interest the same deposit would only reach $19,000.00 — the difference is compounding doing the work.
How to use Compound Interest Calculator
- 01Enter your starting amount, annual interest rate and the number of years.
- 02Add a regular contribution if you plan to keep paying in.
- 03Choose how often interest compounds and read the growth table and total interest earned.
About Compound Interest Calculator
Compound interest is calculated with A = P(1 + r/n)^(nt), where P is the principal, r the annual rate as a decimal, n the number of compounding periods per year and t the number of years. Regular contributions are added period by period on top of that.
Compounding frequency has a smaller effect than people expect: at 6 percent, monthly compounding beats annual by roughly a sixth of a percentage point a year. Time in the market and contribution size matter far more.
The figures are a projection, not a forecast. Real investment returns vary year to year, and this model assumes a steady rate throughout.
Frequently asked questions
- What is the compound interest formula?
- A = P(1 + r/n)^(nt) — principal, annual rate, compounds per year, and years.
- Does compounding frequency matter much?
- A little. Monthly beats annual by a fraction of a percent a year at typical rates.
- Are returns guaranteed?
- No. This is a projection using a fixed rate, not a prediction of actual investment performance.
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