Percentage Calculator

Six calculation types — pick the one that matches what you actually need to find

The tab row at the top switches between six modes. X% of Y answers "what is 20% of 150?" What percent answers "30 is what percent of 150?" Find the whole works backwards — if 30 is 20%, what is the full amount? Percentage change takes an old value and a new value and tells you the growth or drop. Percentage difference compares two values without assuming either is the reference point. Apply percentage adds or subtracts a given percent — useful for discounts, tips, and tax. Each mode shows only the fields it needs, so there's nothing irrelevant on screen.

Step-by-step working and the formula reference panel

Every result comes with a step-by-step breakdown showing each arithmetic stage — not just the answer, but the intermediate values. This is useful when you need to explain the calculation to someone or double-check that the right formula was applied. A sidebar on the right lists the four core formulas in shorthand: X% of Y, what percent, percentage change, and percentage difference. Below that, worked examples show results like 20% of 150 = 30 and 100 → 120 = 20% increase, so you can cross-check your own numbers against a known case.