Calculate simple interest
Work out simple interest on a principal amount over a given rate and time.
The starting amount and annual interest rate.
How many years the interest accrues for.
The final amount, and the interest earned.
Frequently asked
How is simple interest calculated?
SI = P × R × T / 100, where P is the principal, R is the annual rate, and T is the time in years. Unlike compound interest, it's always calculated on the original principal only.
When is simple interest used?
Some short-term loans, certain bonds, and a few deposit schemes use simple interest. Most savings and investment products (FDs, RDs, mutual funds) compound instead.
When would I use this over the Compound Interest Calculator?
When the product or loan explicitly uses simple interest, check the terms. Most everyday savings products compound instead, so use Compound Interest, FD, or RD for those.
Does the rate compound if I extend the time period?
No, simple interest is always calculated on the original principal only, no matter how long the period, which is the defining difference from compound interest.
Can I calculate the rate needed to reach a target amount?
Not directly, this calculator solves for the maturity value from principal, rate, and time. Rearrange the formula (R = SI × 100 / (P × T)) to solve for rate instead.
Is simple interest ever better for the borrower?
Yes. Since interest never compounds, the total interest paid on a simple-interest loan is lower than an equivalent compound-interest loan at the same nominal rate over the same period.