What is it?
The Simple Interest Calculator works out the interest on an amount at a yearly rate for a number of years. It shows the interest and the total amount.
Who is it for?
Students solving school and competitive-exam problems, people lending or borrowing privately, and anyone checking interest on late payments.
How to use it
- Enter Principal, yearly Interest rate and Time in years.
- Read the interest and total.
- Copy or share the result.
The answer appears as you type; there is no Calculate button. Tap Copy result to copy it, or Share on WhatsApp to send it.
The formula
Simple interest = P × R × T ÷ 100. ₹10,000 at 5% for 3 years earns ₹1,500, so the total is ₹11,500. Interest is charged only on the original amount, never on interest.
Time in months or days
- Time is in years: 6 months is 0.5, 18 months is 1.5.
- For days, divide by 365: 90 days is about 0.2466 years.
- If a rate is quoted per month (like 2% a month in private lending), multiply by 12 for the yearly rate: 2% a month = 24% a year.
Where simple interest is used
- School and competitive-exam maths.
- Some short-term loans between people, and interest on late payments in contracts.
- Many “flat rate” personal and vehicle loans: they look cheap but cost more than the same rate on a reducing balance.
Bank deposits and most loans use compound interest. See the Compound Interest Calculator, or the FD Calculator for bank deposits.
Errors and how to fix them
- Empty result: fill in principal, rate and time.
- Monthly rate typed as yearly: multiply a monthly rate by 12 first.
Open the tool: Simple Interest Calculator
Still stuck?
Contact support. Tell us which tool or page you were using, what you tapped, what you saw, and your phone or computer and browser (for example: Android phone, Chrome). We reply by email.
Questions, or an error not listed here?
Tell us in the comments: what you were doing, the exact message you saw, and your device and browser. We read every comment and add new fixes to this article.