Calculatree

Compound Interest Calculator

Watch a starting amount plus monthly deposits compound into a future balance.

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Updates live as you type

How it works

Compounding earns returns on your returns, so growth accelerates the longer money stays invested. This calculator combines a lump-sum start with steady monthly deposits to show how a modest, consistent habit can become a large balance.

Frequently asked questions

Why does the interest dwarf my contributions over time?

Early on, most of the balance is money you put in. Given enough years, compounding takes over and the growth on prior growth can exceed everything you contributed — the core reason to start early.

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