About the Simple Interest Calculator
Simple interest is calculated only on the original principal amount, unlike compound interest, which also earns interest on previously accumulated interest. It's commonly used for certain personal loans, some short-term promissory notes, and as the basic starting concept when interest is first taught.
This calculator uses the classic simple interest formula — Interest = Principal × Rate × Time — to show both the interest amount and the total balance (principal plus interest) at the end of the specified time period.
Frequently Asked Questions
What's the difference between simple and compound interest?
Simple interest is calculated only on the original principal for the entire period. Compound interest recalculates and adds interest on the growing balance at each compounding period, which produces a larger total over time on the same rate and duration.
Where is simple interest actually used?
Some auto loans, certain short-term personal loans, and basic bonds use simple interest calculations, though most savings accounts, credit cards, and mortgages use compound interest instead.
Can I use this for a time period in months instead of years?
Yes — convert months to a decimal year first (e.g., 6 months = 0.5 years) before entering the time period, since the formula expects time in years.