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Compound interest formula calculator

Calculate compound interest using the standard formula A = P(1 + r/n)^(nt), where P is the principal, r is the annual rate, n is the number of times interest compounds per year, and t is the time in years. This calculator shows your final balance, total interest earned, and a full year-by-year breakdown. All calculations run locally in your browser.

Compound frequency

1 yr50 yrs

Formula: A = P(1 + r/n)^(nt) — where P = principal, r = annual rate, n = compounds/year, t = years

How it works

The compound interest formula is A = P(1 + r/n)^(nt), where P is the principal, r is the annual interest rate as a decimal, n is the number of compounding periods per year, and t is the number of years. The year-by-year table recalculates each row using this formula with increasing t values. All arithmetic runs in JavaScript in your browser.

Processing runs in your browser

All calculations happen locally in your browser tab. Our servers are not involved at any point.

Related operations

For working out a quick percentage of a value, try the percentage calculator. To convert fractional rates into decimals, use the fraction calculator. For tipping or splitting bills based on totals, see the tip calculator.

Frequently asked questions

What is the compound interest formula?
A = P(1 + r/n)^(nt). P = principal (starting amount), r = annual interest rate (as a decimal), n = compounding frequency per year, t = time in years. A is the final balance including interest.
What is the difference between compound and simple interest?
Simple interest is calculated only on the principal. Compound interest is calculated on the principal plus any previously earned interest, so your interest earns interest. Over long periods, the difference is substantial.
How does compounding frequency affect growth?
The more frequently interest compounds, the faster your money grows. Daily compounding produces slightly more than monthly, which produces more than annual. The difference becomes more pronounced over longer periods and at higher rates.
Is my data sent to a server?
All calculations run locally in your browser using JavaScript. No data is sent to our servers.

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