Simple Interest Calculator
Calculate simple interest instantly. Principal, annual rate, and time period. I = P x r x t
How to Use
Enter your values in the fields above and click Calculate to get instant results. All computations run locally in your browser. No data is ever uploaded or stored.
Related Calculators
Simple Interest vs. Compound Interest
Simple interest is calculated only on the original principal: I = P × r × t, where P is the principal, r is the annual rate, and t is the time in years. Unlike compound interest, simple interest does not grow on previously earned interest — making it easier to calculate and predict.
A $10,000 deposit at 5% simple interest for 3 years earns $1,500 total interest ($500 per year). The same deposit with compound interest would earn more because each year's interest is added to the balance before calculating the next year's return.
Simple interest is commonly used for short-term personal loans, auto loans, and some bonds. For longer-term savings and investments, compound interest yields higher returns. Compare both methods using CalcSolver's compound interest calculator to see the difference over time.
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Frequently Asked Questions
What is simple interest?
Simple interest is calculated only on the original principal. The formula is I = P × r × t, where P is principal, r is annual rate, and t is time in years. Unlike compound interest, it does not earn interest on interest.
When is simple interest used?
Simple interest is commonly used for short-term loans, some auto loans, and certain savings accounts. Most long-term investments and mortgages use compound interest.
How does simple interest differ from compound interest?
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