Instantly find interest earned and total repayment
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Formula: SI = P × R × T where P = Principal, R = Annual Rate (as a decimal), T = Time in years. Total = P + SI. Simple interest does not compound — interest is calculated only on the original principal. All calculations run locally in your browser.
The simple interest calculator computes interest earned or owed using the classic SI = P × R × T formula. Enter your principal, annual interest rate, and time period in years, months, or days to instantly see how much interest accrues and the total amount due or received. Ideal for personal loans, short-term deposits, and quick financial estimates.
Simple Interest = Principal × Rate × Time, where Rate is the annual percentage rate expressed as a decimal and Time is in years. For example, $10,000 at 5% for 3 years earns $1,500 in interest.
Simple interest is calculated only on the original principal, so each period accrues the same dollar amount of interest. Compound interest also charges interest on previously accumulated interest, making it grow faster over time.
Yes. The calculator accepts years, months, or days and automatically converts to the equivalent fraction of a year before computing. For example, 18 months is treated as 1.5 years.
Simple interest is common for short-term personal loans, auto loans, some savings accounts, US Treasury bills, and promissory notes. It is generally more borrower-friendly than compound interest for loans.