Interest Calculator (Simple and Compound)

Earned Compound Interest

Interest is calculated on the principal, regular deposits, and interest already earned. Edit any field; results update live.

Principal

Regular deposit

Deposit frequency

Annual Interest rate (%)

Time (years)

Compounding frequency

Regular deposit total —

Total deposited —

Interest earned —

Total amount —

Equivalent APR (%) —

A = P(1 + r/n)^nt plus each regular deposit grown to the end of the term. Deposits are made at the end of each deposit period. P principal, r annual rate as a decimal, n compounds per year, t years. Equivalent APR is the effective annual rate: the yearly return you would need with once-a-year compounding to match your nominal rate and compounding frequency ((1 + r/n)ⁿ − 1). Interest earned is the total amount minus principal minus all deposits paid in.

Simple Interest

Interest is calculated on the principal only. Edit any field; results update live.

Principal

Annual Interest rate (%)

Time (years)

Interest earned —

Total amount —

I = P × r × t · A = P + I · r is the annual rate as a decimal, t is time in years.