Enter an amount, an annual interest rate and a time period to calculate simple interest and the total amount. Choose years, months or days; the calculator converts the time to years for you.
How the simple interest calculator works
Simple interest is calculated on a constant principal. With an annual percentage rate R, principal P and time T in years, interest = P × R × T ÷ 100. The total amount is the principal plus this interest.
For example, ₹15,000 at 5% a year for two years produces ₹1,500 of simple interest, giving a total of ₹16,500. These are illustrative inputs, not a bank offer.
Calculate simple interest for months or days
For months, the calculator divides the duration by 12. ₹10,000 at 12% a year for eight months produces ₹800 of interest and a total of ₹10,800.
For days, this tool uses a 365-day year. ₹50,000 at 10% for 90 days produces ₹1,232.88 of interest, rounded to the nearest paisa, and a total of ₹51,232.88. A contract may use a different day-count convention, so check its terms when comparing an actual quote.
What this result includes
The calculation assumes a constant principal and rate for the whole period. It does not include compounding, instalment repayments, fees, tax, penalties or changes in interest rates. It is a mathematical illustration, not a quote for a particular deposit or loan.
Common questions
Can I enter a fraction of a year?
Yes. Enter 0.5 years or select six months. Both represent half a year and produce the same result.
How is simple interest different from compound interest?
Simple interest uses only the original principal. With compounding, interest added to the balance also earns interest in later periods. This calculator uses simple interest throughout.
What happens at a zero interest rate?
Interest is zero and the total equals the principal. A zero time period also gives zero interest.
Calculator checked on 26 September 2026. Results are rounded to two decimal places for display.
Last Updated on 1 month ago by Team Paisaseekho
