The Compound interest calculator
What a starting amount and a regular deposit grow into once the interest starts earning interest of its own. Year by year, with tax and inflation if you want them.
Your savings
3 · What it is really worth
All optional. Leave them empty for the plain compound interest figures.
Everything is worked out in your browser. No figure is sent anywhere.
How to use the Compound interest calculator
- Type what you are starting with, what you will add each month and the rate you expect.
- Type your own numbers. The result updates as you type.
- Copy the result, or change an assumption and watch what it does.
Frequently asked questions
What is compound interest?
Interest paid on the interest you have already earned, as well as on the money you put in. It is why the same rate over twenty years is worth so much more than twice the same rate over ten, and why the year by year table below curves upward rather than climbing in a straight line.
How exact is it?
The arithmetic is exact and rounded the way money is, at the cent. What it cannot know is anything specific to you, so read it as the ordinary case rather than as advice.
Is anything uploaded?
Every figure is worked out in your browser. Nothing is uploaded, there is no sign-up, and no result is stored anywhere but on your own device.
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