Compound Interest Calculator

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Watch your money grow exponentially with compound interest. Unlike simple interest (which only earns on your initial investment), compound interest earns on the ever-growing balance — this is why time in the market matters more than timing the market.

Our calculator shows the final balance, total contributions, and how much of your gains come from interest vs. what you put in. Compound monthly contributions alongside your initial investment to see the most dramatic growth over 10, 20, or 30 years.

Formula
FV = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) − 1) / (r/n)]

FAQ

What is the "magic of compound interest"?
Compound interest earns interest on both your principal AND previously earned interest. Albert Einstein called it the 8th Wonder of the World — it turns small, regular investments into large sums over decades.
Is compound or simple interest better for investors?
Compound interest always favors investors because the base grows over time. Simple interest only earns on the original principal, so it grows linearly.

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