Compound Interest Calculator
See how your money grows with compounding over time.
What is Compound Interest?
Compound interest is interest calculated on both the original principal and the interest already accumulated from previous periods, which is why it grows faster than simple interest over time. This calculator uses the formula A = P(1 + r/n)ⁿᵡ, where P is the principal, r is the annual rate, n is how many times per year interest compounds, and t is the time in years.
How to use it
- Enter your starting principal, annual interest rate and the number of years.
- Choose how often interest compounds — annually, semi-annually, quarterly, monthly or daily.
- Read off the interest earned and the final amount.
More frequent compounding produces a slightly higher return for the same nominal annual rate, because each smaller period's interest starts earning interest sooner; the difference between monthly and daily compounding is usually small, but the difference between annual and monthly compounding can be meaningful over long periods. This calculator is often used to estimate how a savings account, certificate of deposit, or long-term investment might grow, and to compare offers that quote the same rate but compound on different schedules.