Simple Interest Calculator
Calculate simple interest and the total amount from principal, rate and time with this free online simple interest calculator, using I = P × r × t.
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How to use Simple Interest Calculator
- 1Enter the principal amount and pick a currency
- 2Enter the annual interest rate and the time in years, months or days
- 3Read the interest earned and total amount, and open the year-by-year breakdown
Frequently asked questions
What is the simple interest formula?▾
Simple interest is I = P × r × t, where P is the principal, r is the annual rate as a decimal and t is the time in years. The total amount is P + I.
What is the difference between simple and compound interest?▾
Simple interest is only ever charged on the original principal. Compound interest is also charged on interest already added, so it grows faster over time.
How do I calculate simple interest for months or days?▾
Convert the time to years first: divide months by 12 or days by 365. The calculator does this for you when you pick months or days.
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