Simple Interest Calculator
Enter a principal amount, an annual interest rate, and a time period in years to calculate the simple interest earned and the total amount (principal plus interest). The formula SI = (P x R x T) / 100 is displayed alongside the result so you can verify the calculation.
Simple interest is used for short-term loans, fixed deposits in some banks, car loans, and personal loans where interest is not compounded. Unlike compound interest, simple interest is calculated only on the original principal — the interest does not itself earn interest.
This calculator is useful for quickly estimating returns on savings instruments that use simple interest, understanding the cost of a short-term loan, or checking homework and exam problems involving the SI formula.
By The Paper Room Editorial Team — Calculator Tools
Frequently asked questions
What is the simple interest formula?▼
Simple Interest = (Principal x Rate x Time) / 100, where Principal is the initial amount, Rate is the annual interest rate in percent, and Time is the duration in years. The total amount is Principal + Simple Interest.
How is simple interest different from compound interest?▼
Simple interest is calculated only on the original principal throughout the entire period. Compound interest is calculated on the principal plus any previously accumulated interest. Over time, compound interest grows faster because interest earns interest.
When is simple interest used in practice?▼
Simple interest is commonly used for short-term personal loans, auto loans, some fixed deposits, treasury bills, and student loans during the grace period. Most long-term savings and investment products use compound interest instead.