Percentage Calculator
Solve any percentage problem: find X% of a number, what percent one number is of another, or the percent change between two values.
How it works
Percentage formulas
X% of Y = (X / 100) × Y X as a percent of Y = (X / Y) × 100 Percent change = ((New − Old) / |Old|) × 100
A percentage is a fraction of 100. All three problems are the same relationship rearranged: part = percent × whole. Pick the version that matches what you know and what you want to find.
Worked example
What is 15% of 200? → (15 / 100) × 200 = 30. Reversed: 30 is what percent of 200? → (30 / 200) × 100 = 15%. And going from 200 to 230 is a (230 − 200) / 200 × 100 = 15% increase.
Frequently asked questions
How do I calculate a percentage of a number in my head?
Find 10% by moving the decimal one place left, then scale. For 15% of 200: 10% is 20, 5% is half of that (10), so 15% is 30.
What is the difference between percent change and percentage points?
Going from 10% to 15% is a change of 5 percentage points, but a 50% relative increase. Percent change compares relative size; percentage points compare absolute difference between two percentages.
Can percent change be more than 100%?
Yes. Going from 50 to 150 is a 200% increase. A decrease, however, cannot exceed 100% — losing 100% means reaching zero.