Simple Interest Calculator
Free simple interest calculator. Work out simple interest and the total amount for any principal, rate and time — instantly, with rupee formatting, in your browser.
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Free Simple Interest Calculator
This free online simple interest calculator works out the interest and total amount on a loan or deposit in seconds. Enter the principal, the annual interest rate and the time period — in years or months — and instantly see the simple interest and what you will repay or receive in total. It’s free, accurate and runs entirely in your browser.
How to use the simple interest calculator
- Enter the principal — the amount borrowed or deposited.
- Set the annual interest rate (percent per year).
- Enter the time period and choose years or months.
- Read off the simple interest and the total amount (principal plus interest).
- Use the breakdown chart to see how much of the total is interest.
Simple interest vs compound interest
Simple interest is charged only on the original principal. The formula is
SI = P × R × T / 100, where P is the principal, R is the annual rate and
T is the time in years. The total amount you repay or receive is Total = P + SI. If your
time is in months, convert it with T = months / 12. For example, ₹10,000 at 8% for 5 years gives
₹4,000 of interest and a total of ₹14,000.
Compound interest is different: it is charged on the principal plus any interest already added, so it grows faster over time. Simple interest stays flat each period, which makes it common for short-term personal loans, car loans and certain fixed deposits. Because the interest never compounds, simple interest is easier to predict and usually works out cheaper for the borrower than compound interest at the same rate.