Money calculator

Compound interest calculator

Interest that earns interest. Works for savings, loans and maths homework, with the working shown.

Principal (₹)

Rate of interest (% per year)

Time (years)

Compounded

Amount (A)

–

–compound interest

–simple interest, for comparison

–extra from compounding

Year by year

Compound interest formula

A = P (1 + r ÷ 100k)ᵏᵗ CI = A − P

P is the principal, r the rate % per year, k how many times interest is added each year and t the time in years. In Class 8 maths, "compounded half-yearly" means k = 2: halve the rate and double the number of periods.

Why is compound interest more than simple interest?

Simple interest is always worked out on the starting amount. Compound interest is worked out on the amount plus interest already added, so each period earns a little more than the last.

What about depreciation or population growth?

They use the same formula. For a value that falls each year, use A = P (1 − r ÷ 100)ᵗ instead.