Calculators
Simple Interest Calculator
Calculate simple interest and total repayment from principal, rate and time.
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Interest earned
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Total amount
About this tool
Simple interest is charged only on the original principal — the model behind many short-term loans, deposits and homework problems. Enter principal, annual rate and time to get the interest and total amount instantly.
Compare with the Compound Interest Calculator to see how dramatically compounding changes long-term results.
How to use
- Enter principal, rate and time in years.
- Read the interest and total amount.
Frequently asked questions
Interest = P × R × T ÷ 100 — principal times annual rate times years.
Simple interest never earns interest on interest; compound does, so it grows faster over time.
Yes — enter fractions of a year: 6 months is 0.5.