Compound Interest Calculator

Compound interest is interest earned on both your original money and on interest already credited. This calculator shows the final balance, what you put in, and how much growth compounding added.

You can add a contribution each compounding period (for example a monthly deposit into a savings account) to model real saving habits.

The formula

A = P(1 + r/n)^(nt) + C · ((1 + r/n)^(nt) − 1) / (r/n)

Worked example

$1,000 at 10% compounded yearly becomes $1,210 after 2 years — $210 of interest, $10 of it earned on the first year's interest.

The example is pre-loaded in the result panel — press Calculate with your own numbers to replace it.

Frequently asked questions

What is the difference between simple and compound interest?

Simple interest is paid only on the original principal. Compound interest is also paid on previously earned interest, which is why balances accelerate over long periods.

Does compounding frequency matter much?

Slightly. At the same stated rate, daily compounding beats yearly by a small margin — the effect grows with the rate and the time period.

Category: Finance calculators

Sources & methodology

This calculator applies the formula shown on this page exactly as written, using the standard definitions for its inputs. Results are computed from the values you enter — no data is stored — and are rounded only for display.

Content last reviewed 2026-10-21 by CalcHub Editorial.

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Final balance	$1,210.00
Total you put in	$1,000.00
Interest earned	$210.00

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