Simple Interest Calculator
Simple interest is charged only on the original amount, which makes it common for short-term loans between businesses and friends. Enter the time in months to include part of a year.
How it works
Interest = principal × rate × years ÷ 100. For 10,000 at 9% a year for 18 months, the time is 1.5 years, so the interest is 10,000 × 9 × 1.5 ÷ 100 = 1,350, and the total is 11,350.
Questions
What is the difference between simple and compound interest?
Simple interest is always worked out on the original amount. Compound interest is also charged on interest already added, so it grows faster.
Can I enter days?
The time field uses months. For days, divide by 30 for a rough figure, or use the late payment calculator, which works in days.
Does the rate have to be yearly?
Yes. If you have a monthly rate, multiply it by 12 first.
Results are estimates for planning. They are not tax, legal or financial advice.
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