💰 Simple Interest Calculator

About this Simple Interest Calculator

Simple interest is charged or earned only on the original principal, never on interest already added — the formula is principal × rate × time ÷ 100. It is used for short loans, some bonds and basic classroom maths. This calculator shows the interest and the final total, and makes a good contrast with compound interest, where the balance grows faster because interest itself earns interest.

How to use it

1. Enter the principal — the starting amount of the loan or deposit.
2. Enter the yearly interest rate as a percentage.
3. Enter the time in years (use 0.5 for six months).
4. Click Calculate interest to see the interest earned and the final total.

Example

A principal of 100,000 at 10% per year for 3 years earns simple interest of 30,000, giving a total of 130,000 at the end.

Frequently asked questions

What is the difference between simple and compound interest?

With simple interest the interest is always worked out on the original principal. With compound interest, each period interest is added to the balance and then itself earns interest, so the total grows faster.

Can I use months instead of years?

Yes — convert months to years first: 6 months is 0.5 years, 18 months is 1.5 years. The rate must stay the yearly rate.

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