Doodleden

Free calculator

Compound Interest Calculator

See how money grows when interest earns interest. Enter a starting amount, an annual rate, the years and how often interest is added, with regular deposits if you like, and get the balance, the interest earned, the effective annual rate and a year-by-year table.

Calculated in your browser — nothing you enter is stored or sent.

1

Your savings

Amounts are in any currency; the calculator adds no symbol.

Coming soon: deposits on a different schedule from the interest, such as monthly deposits into an account that adds interest yearly, and partial periods. Banks handle these differently, so they need care to get right.

2

Result

Balance
You put in
Interest earned
Effective annual rate

BalanceMoney put in

Year by year

YearBalancePut in so farInterest so far

This is a hypothetical projection at a fixed rate. Real savings and investments can earn more or less, rates change, and fees, taxes and inflation reduce what you keep. It is not financial advice.

How compound interest is worked out

With a nominal annual rate r added n times a year, each period multiplies the balance by 1 + r/n. After m whole periods a starting amount P becomes P(1 + r/n)^m. Regular deposits C at the end of each period add C((1 + r/n)^m − 1)/(r/n); deposits at the start earn one more period of interest, so that amount is multiplied by 1 + r/n.

Adding interest more and more often approaches continuous compounding, Pe^(rt). The What is e? section of the Exponential Growth Calculator shows why.

The effective annual rate is what the balance actually grows by in a year: (1 + r/n)^n − 1, or e^r − 1 when continuous. It can differ from a bank's quoted APY, which follows its own rules.

Only whole periods are counted: 10.5 years of yearly compounding counts 10 periods, and the result says how many periods it used.

Private by design

Every number is calculated in your browser. Nothing you enter is sent to Doodleden or stored.

Calculations run in your browser and are not uploaded to or stored by Doodleden. This site is funded by advertising; our ad partners use cookies and similar technologies as described in our privacy policy.