Calculate simple interest on a principal amount
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Results are estimates, not financial advice. Rates, charges and rules change, so confirm with your bank, post office or a financial adviser before you decide. Terms of use
How to Use
- Enter the Principal amount, the sum you start with.
- Enter the Rate of interest (% per year).
- Choose years, months or days and enter the Time period.
- The Simple interest and Total amount change as you type, with the P × R × T ÷ 100 working shown. Tap pdf or copy result to keep it.
Simple interest formula
Here P is the principal, R is the rate per year (%), and T is the time in years. The simple interest calculator above does this for you and shows the working.
Where simple interest is used
- Short-term personal loans and gold loans
- Car loans from some lenders
- Interest on late payments or arrears
- Quantitative aptitude sections of competitive exams (SSC, banking, UPSC)
Simple vs compound interest
Simple interest grows in a straight line, because interest is always worked out on the original principal. Compound interest grows faster and faster, because the interest you've already earned starts earning interest too. Over long periods, the gap gets big. Put ₹1 lakh at 8% for 10 years: simple interest adds ₹80,000, while compound interest (yearly) adds ₹1,15,892.