Simple Interest Calculator
🔒 In your browserSimple interest and total amount from principal, rate & time.
How it works
Calculate simple interest, where interest is charged only on the original principal. Enter the principal, the annual rate and the time in years.
Simple interest uses only the principal. Most loans and deposits actually compound — use the Compound Interest Calculator for those.
🔒 Calculated entirely in your browser — nothing is uploaded.
🔒 Calculated in your browser: your loan, investment and salary figures are never uploaded. Interest, tax and salary structures vary by bank and employer, so treat the result as a close estimate and confirm exact figures with them.
About the Simple Interest Calculator
This free simple interest calculator finds the interest and total amount on a principal, where interest is charged only on the original sum. Enter the principal, the annual rate and the time in years for an instant result.
It calculates in your browser — quick and private.
How simple interest works
Simple interest is a flat charge on the principal alone: SI = P × r × t ÷ 100, where P is the principal, r the annual rate and t the time in years. Unlike compound interest, it never charges interest on previously earned interest, so it grows in a straight line rather than a curve.
A worked example
On ₹1,00,000 at 10% for 5 years, the simple interest is 1,00,000 × 10 × 5 ÷ 100 = ₹50,000, making the total ₹1,50,000. The same amount under compound interest would earn more (₹61,051 annually compounded), because compounding adds interest to the balance each year while simple interest does not.
Frequently asked questions
What is the simple interest formula?
SI = P × r × t ÷ 100, where P is the principal, r the annual rate and t the time in years. The total amount is the principal plus this interest.
When is simple interest used?
It's common for short-term loans, some vehicle and gold loans, and quick estimates. Most bank deposits and long-term loans compound instead.
How does it differ from compound interest?
Simple interest is charged only on the principal, so it's always lower than compound interest at the same rate and time. Use the Compound Interest Calculator to compare.
Does the time have to be in years?
The formula uses years, so convert months to a fraction of a year — 6 months is 0.5. The calculator expects the time in years.
Is my data uploaded?
No. The calculation runs entirely in your browser.