Simple interest calculator
Interest on the principal, without compounding.
Principal plus simple interest
For illustration only. Read the assumptions below for the full picture.
Understand your result.
Calculate interest on an unchanged principal without interest-on-interest. Choose a period in years, months or days using the stated 365-day convention.
The interest amount is added to principal once for the entered term. It differs from a compound-interest projection at the same nominal rate.
A worked example.
Using this calculator’s default inputs, principal plus simple interest is ₹1,24,000. This is an illustration of the stated formula, not a forecast.
See the example inputs
| Investment amount | ₹1,00,000 |
|---|---|
| Annual simple interest rate | 8 % |
| Time period | 3 time units |
| Time is measured in | Years |
A common mistake to avoid
Using a simple-interest result for a reducing-balance EMI loan.
Questions you might have.
Does it use actual leap-year days?
No. Day-based periods are divided by 365; a contract may specify another convention.
Can I compare it with compound interest?
Yes, provided the principal, rate and period conventions are aligned.
Prepared by INDwise · Calculation checks: 29 October 2026 · How we check the maths · Report a correction
How we calculate it
Simple interest = principal × annual rate × years. Maturity = principal + simple interest. Months are divided by 12; days by 365.
Assumptions & things to know
No interest on interest. Fixed rate and unchanged principal, no fees or tax. Real lending contracts can use a different day-count convention.
Your privacy & sharing
Your financial inputs are used only within this page. Saved calculators use this browser’s local storage. Sharing creates a link with the entered values, so anyone with that link can see those values. A downloaded summary stays on your device.