Compound interest calculator
See how your savings can grow when interest earns interest, with optional monthly deposits, in any currency.
How compound interest works
Compound interest means you earn interest on your interest. Each time interest is added, it becomes part of the balance that earns the next round. The longer you leave it, the faster it grows.
The rule of 72
A quick way to estimate how long money takes to double: divide 72 by the yearly interest rate. At 12% a year, money doubles in about 6 years. At 8% it takes about 9.
Why inflation matters
Interest rates and inflation both move. If inflation is higher than your interest rate, your balance grows but buys less. Add the inflation box above to see the real value.
Common questions
What is the difference between simple and compound interest?
Simple interest is paid only on your original amount. Compound interest is paid on your original amount plus the interest already added, so it grows faster over time.
Does it matter how often interest is added?
A little. Adding interest more often, such as monthly instead of yearly, gives slightly more at the same stated rate. The size of the rate and the number of years matter far more.
Is this what my savings app or fund will pay?
No. Real rates change and some products do not pay a fixed rate. Use the rate your provider quotes, and treat the result as an estimate. Tax and fees are not included.
Can I use this for T-bills or fixed deposits?
You can, if you enter the yearly rate and choose how often interest is added. Check the provider's terms for how returns are paid, because some pay interest upfront or at the end.
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