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FINMATHLY / TOOLS & RESOURCES

Compound Interest Calculator

See how your starting balance and regular contributions could grow.

YOUR NUMBERSUSD
USD. Range 0 to 100000000.
USD. Range 0 to 100000000.
%. Range 0 to 100.
years. Range 1 to 60.

Calculated in your browser. No account required.

Illustrative estimate. Review the assumptions before using the result.

View calculation table

How this calculation works

i = (1 + r / m)^(m / 12) − 1; FV = P(1+i)^n + C((1+i)^n−1)/i.

P is your starting balance, C is the end-of-month contribution, r is the annual nominal rate as a decimal, m is compounds per year, and n is months. At 0% the result is P + C × n. We convert the chosen frequency to an equivalent monthly growth rate.

A worked example

A $1,000 balance at 12% nominal interest, compounded monthly for one year with no contributions, becomes $1,126.83.

Assumptions and limitations

Constant hypothetical returns, end-of-month deposits, and equivalent monthly accrual. No tax, fees, inflation, or market volatility. Actual investment returns are uncertain.

Common questions

Why can my actual result differ?

Constant hypothetical returns, end-of-month deposits, and equivalent monthly accrual. No tax, fees, inflation, or market volatility. Actual investment returns are uncertain.

Are my inputs saved?

The calculator code processes inputs within your browser and does not send them to our server or save them in browser storage. Downloads and copied summaries remain under your control.