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Watch your money grow

Compound interest is the most powerful force in personal finance: every month you earn interest on your interest too. Enter a starting amount, a monthly deposit, an interest rate and a number of years — and see how much you'll have, how much you deposited, and how much the interest did for you.

It answers questions like 'how much will I have if I save $500 a month', 'compound interest calculator' and 'what does 5% interest add up to in 10 years' — showing deposits, interest and balance year by year. See for yourself why starting early beats saving more later, and how small monthly increases bend the whole curve.

Good to know

• Saving $200 a month at 5% for 10 years gives about $31,000 — of which $7,000 is pure interest.
• Interest is compounded monthly.
• Time matters more than the starting amount — starting five years earlier usually beats saving twice as much later.

How it works

1. 1Enter your starting amount and your monthly deposit.
2. 2Enter the annual interest rate and the number of years.
3. 3The projection shows deposits, interest and total balance per year.
4. 4Try raising the monthly deposit a little and watch the interest curve bend.

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