Simple and compound interest calculator
Find the interest earned and the maturity amount, with a year-by-year table and the total written in words.
Result
The formulas
Simple interest: I = P × r × t. Compound interest: A = P × (1 + r/n)^(n × t), where P is the principal, r the yearly rate as a decimal, n the number of compounding periods per year, and t the time in years.
Frequently asked questions
What is the difference between simple and compound interest?
Simple interest is earned only on the original principal: A = P(1 + rt). Compound interest is earned on the principal plus earlier interest: A = P(1 + r/n)^(nt).
What does compounding frequency mean?
It is how often interest is added to the balance in a year: yearly (1), half-yearly (2), quarterly (4), monthly (12) or daily (365). More frequent compounding gives a slightly higher maturity amount.
Is this the same as my bank’s figure?
It may differ slightly because banks apply their own day-count and rounding rules. Treat the result as an estimate.