Simple Interest Calculator
Enter a principal, rate, and time to see the simple interest.
Work out simple interest in seconds. Enter the principal, the annual rate in percent, and the time in years, and this calculator shows the interest earned and the total amount using the formula SI = P times r times t divided by 100. Everything runs in your browser, so nothing is sent anywhere.
How to use
- Enter the principal, the amount you are investing or borrowing.
- Enter the annual interest rate as a percentage, for example 5 for 5 percent.
- Enter the time in years. Decimals like 2.5 are allowed.
- Read the simple interest and the total amount in the results panel.
- Use Copy to grab the figures, or Reset to start over.
Examples
- Principal 10000, rate 5 percent, time 3 years. Simple interest is 1500 and the total amount is 11500.
- Principal 25000, rate 7.5 percent, time 2.5 years. Simple interest is 4687.50 and the total amount is 29687.50.
- Principal 100000, rate 8 percent, time 2 years. Simple interest is 16000 and the total amount is 116000.
FAQs
- What is the simple interest formula?
- Simple interest is SI = P times r times t divided by 100, where P is the principal, r is the annual rate in percent, and t is the time in years. The total amount is the principal plus the interest.
- How is simple interest different from compound interest?
- Simple interest is charged only on the original principal, so it grows by the same amount each year. Compound interest is charged on the principal plus any interest already added, so it grows faster over time.
- Can I use a partial year for the time?
- Yes. Enter a decimal such as 0.5 for six months or 2.5 for two and a half years, and the calculator scales the interest accordingly.
- Which currency does this use?
- None in particular. The calculator works on the numbers you enter and shows results with thousands separators, so you can read them in any currency.
- Why do I get an error message?
- The inputs must be numbers and cannot be negative. If a field is empty, contains letters, or holds a negative value, the calculator shows a short message instead of a result.
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