Compound Interest Calculator

See how your savings or investment grows with compound interest and monthly contributions.

Worked example

You start with 5,000 and add 200 a month at a 7% yearly return. After 15 years you would have about 77,637, of which you put in 41,000. The other 36,637 is growth. The 5,000 alone, with no monthly saving, would become about 14,245.

How to use it

1. Enter what you have now as the starting amount (use 0 if you are starting fresh).
2. Enter how much you can add each month.
3. Enter a realistic yearly return and the number of years. Results are estimates; real returns go up and down.

Same 5,000 start and 200 a month at 7%, over different periods

Common mistakes

• Assuming a high return will continue every year. Use a cautious number and test a lower one too.
• Ignoring inflation. Money 20 years from now buys less than the same amount today.
• Forgetting fees and taxes, which reduce your real return.

Helpful tips

• Time matters more than the amount. Saving 200 a month for 30 years ends far higher than for 20 years, even though you only put in 24,000 more.
• Starting even a few years earlier often beats adding more each month later.

Read the guide

Frequently asked questions

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