Effortless Percent Calculator

This page runs three distinct percentage formulas, each solving for a different unknown. Picking the right one depends on which two numbers you already have.

Formula 1: What is X% of Y?

Result = (X ÷ 100) × Y. Example: what is 20% of 150? (20 ÷ 100) × 150 = 30. Use this when you know a percentage and a total, and need the portion — like calculating a 20% tip on a $150 bill.

Formula 2: X is what percent of Y?

Result = (X ÷ Y) × 100. Example: 30 is what percent of 150? (30 ÷ 150) × 100 = 20%. Use this when you have a part and a whole, and need the percentage — like figuring out what share of a $150 budget a $30 expense represents.

Formula 3: X is Y% of what number?

Result = X ÷ (Y ÷ 100). Example: 30 is 20% of what? 30 ÷ (20 ÷ 100) = 150. Use this when you know a portion and its percentage share, and need the original total — like reverse-engineering a full price from a discounted amount and the discount percentage.

How the three relate

All three formulas describe the same relationship (X = Y% of Z) rearranged to solve for a different variable — the number 20, 30, and 150 appear across all three examples above because they're the same underlying statement viewed from three angles. If you're not sure which section to use, identify which two of the three numbers (part, whole, percentage) you already have.