Enter principal, rate, and time, then click Calculate Interest.

Simple interest is calculated on the original principal amount only, not on accumulated interest. The formula is I = P × r × t, where I is the interest, P is the principal (initial amount), r is the annual interest rate (as a percentage), and t is the time in years. The total amount after interest is A = P + I = P × (1 + r × t). Simple interest is commonly used for short-term loans, bonds, and some savings accounts. Unlike compound interest, simple interest does not compound, making it easier to calculate and understand. This calculator allows you to solve for any variable (interest, principal, rate, or time) when the other three are known. It is essential for financial planning, loan analysis, and understanding the time value of money.

1. Enter three known values among Principal, Rate, Time, and Interest.
2. Leave the field blank for the value you want to calculate.
3. Click the appropriate button: Calculate Interest, Find Principal, Find Rate, or Find Time.
4. The result shows the calculated value with the formula used.
5. Click Reset to restore default example values.