WorldCalcs

Simple Interest Calculator

Work out simple interest and the final balance on any deposit or loan.

Reviewed by the WorldCalcs team · Methodology · Last reviewed: June 2026

Interest

1 500.00

Final balance

11 500.00

Works for any currency — results are in whatever currency you enter.

This is a general estimate, not financial advice. See our Disclaimer.

What is simple interest?

Simple interest is interest calculated only on the original amount (the principal), not on any interest already earned. It is common on short-term loans, car loans and some bonds. Because it ignores "interest on interest", it grows in a straight line and is always less than compound interest over the same period. This calculator shows the interest and the total amount.

How it's calculated

The formula is I = P x r x t divided by 100, where P is the principal, r is the annual interest rate as a percentage, and t is the time in years. The total amount owed or earned is the principal plus the interest, P + I.

Example

10,000 at 5% simple interest for 10 years earns 10,000 x 5 x 10 divided by 100 = 5,000 in interest, for a total of 15,000. A smaller 2,500 at 7.5% for 3 years earns 562.50, for a total of 3,062.50.

All calculations happen in your browser. Nothing is sent, stored, or tracked.

Results are estimates and may contain errors — for general information only, not professional advice. Always verify before relying on them. Disclaimer

How to use

Enter the principal, the annual interest rate, and the time in years. The interest and final balance update instantly as you type.

Interest is the extra amount earned (or owed). Final balance is the principal plus that interest.

Frequently asked questions

What is simple interest?+

Interest charged only on the principal, not on accumulated interest.

How is simple interest calculated?+

With I = P x r x t divided by 100; the total is principal plus interest.

What is the difference between simple and compound interest?+

Compound interest also earns interest on previous interest, so it grows faster. See our Compound Interest Calculator.

When is simple interest used?+

Often on short-term loans, car loans and some bonds.

Is simple interest better for a borrower?+

Usually yes; over the same rate and term it costs less than compound interest.

Does simple interest grow in a straight line?+

Yes; the same amount is added each period, so it is linear.

How do I find the total amount?+

Add the interest to the principal (P + I).

Is this exact for my loan?+

It is an estimate; real loans may add fees, so check with your lender.

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