Compound Interest Calculator
See how your savings or investment grow with compound interest. Add monthly contributions, choose the compounding frequency and get a year-by-year table.
Runs in your browser. Nothing is uploaded.
- Final balance
- –
- Total paid in
- –
- Total interest
- –
| Year | Contributions | Interest | Balance |
|---|
About this tool
Compound interest means you earn interest on your interest. This calculator shows how a starting amount grows over time, with an optional deposit every month. Enter your initial amount, the monthly contribution, the annual interest rate, the number of years and how often interest is compounded.
You get the final balance, the total you paid in and the total interest earned, plus a year-by-year table with the contributions, interest and balance for every year. Interest is calculated monthly at an effective rate equivalent to your chosen compounding frequency, and monthly deposits are added at the end of each month. Figures are estimates for planning, not financial advice, and they ignore taxes, fees and inflation. Your numbers stay in your browser.
How to use it
- Enter your initial amount and, if you plan to save regularly, the amount you will add each month.
- Type the expected annual interest rate as a percentage and the number of years you will let the money grow.
- Choose how often the interest is compounded: yearly, half-yearly, quarterly, monthly or daily.
- Read the totals at the top and scroll through the table to see how the balance develops each year.
Frequently asked questions
What is the compound interest formula?
For a single deposit, the final amount is the principal multiplied by (1 + r/n) raised to the power n × t, where r is the annual rate, n the number of compounding periods per year and t the number of years.
Does compounding more often make a big difference?
A little. At 5% over 10 years, 10,000 grows to about 16,289 with yearly compounding and about 16,487 with daily compounding. Time and regular contributions matter far more.
When are the monthly contributions added?
Each contribution is added at the end of the month, after that month’s interest has been calculated, so a deposit starts earning interest the following month.
Does this include taxes or inflation?
No. The results are nominal and before taxes, fees and inflation. Real returns are usually lower, so treat the numbers as an estimate.
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