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Compound Interest Calculator
Compounding means each period earns a return on the returns already collected, so growth curves upward instead of running in a straight line. Enter a starting amount, a monthly deposit, an expected annual rate and a horizon to see the balance year by year.
How to use it
- Enter what you start with and what you add each month.
- Set the annual return and how many years the money stays invested.
- Choose how often interest is compounded and read the yearly table.
Examples
- 1,000 start, 100 a month, 8% for 10 years → about 20,600, of which roughly 6,600 is interest.
- Add ten more years at the same rate and the balance passes 65,000 — most of the gain arrives late.
- Cut the rate to 4% and the same twenty years end near 40,000, showing how much the rate matters over time.
Questions people ask
Is the result adjusted for inflation?
No. Everything is in today's nominal figures. To reason in real terms, enter your expected return minus expected inflation — a 7% return with 3% inflation becomes 4% here, and the answer is then in today's purchasing power.
Does compounding frequency change much?
Less than people expect. At 8%, moving from yearly to monthly compounding adds a few tenths of a percent per year. The size of the deposit and the number of years matter far more than the compounding interval.
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Updated: 2026-08-07