Compound Interest Calculator

Watch your savings snowball — see the final balance, total interest earned, and a year-by-year growth table.

Starting principal ($)

Annual interest rate (%)

Compounds per year

Years

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How it works

Compound interest means you earn interest on your interest. The formula is A = P(1 + r/n)^nt, where P is the starting amount, r the annual rate as a decimal, n how many times per year interest compounds, and t the years. More frequent compounding grows money slightly faster — monthly beats annually at the same rate. The table shows each year-end balance so you can see growth accelerate: later years add far more than early ones, which is why starting early matters so much.