Finance Tools

Simple Interest Calculator

Calculate simple interest for loans or investments by year, month, or day. Instantly view interest earned and total maturity amount.

Principal Amount

Annual Interest Rate (%)

Duration

Duration Unit

How to calculate simple interest

Enter principal, rate, and time — get interest and total amount instantly.

01
Enter principal, rate, and time
Enter the principal amount, annual interest rate, and time period in years, months, or days.
02
See the interest and total
The interest amount and total maturity value appear instantly.
03
Review the period breakdown
See how interest accumulates over each period for the full duration.

What people use it for

Short-term loans

Calculate the interest on a short-term personal loan or informal lending arrangement.

Fixed deposits

Some fixed deposits use simple interest. Calculate the maturity amount before opening an account.

Treasury bills

Government treasury bills use simple interest. Calculate returns before investing.

Comparing with compound interest

See how simple interest compares to compound interest for the same principal and rate.

Educational purposes

Understand the basic interest formula before moving on to compound interest calculations.

Frequently asked questions

Free, no account needed.

Simple interest is calculated only on the original principal, not on accumulated interest. Formula: I = P × R × T.

Simple interest is used for short-term loans, some fixed deposits, treasury bills, and informal lending.

Simple interest is calculated only on the principal. Compound interest is calculated on the principal plus previously earned interest, so it grows faster over time.

No. All calculations happen in your browser. Nothing is sent to any server.

Yes, in any modern mobile browser.

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