Math Calculator
Percentage Calculator
Find any percentage calculation: what is X% of Y, percentage change between two numbers, or add/remove a percentage.
How to Calculate Percentages
A percentage is a number expressed as a fraction of 100. The word comes from the Latin "per centum" meaning "by the hundred." Percentages are used everywhere — from exam scores and sales discounts to tax rates and investment returns.
Basic Percentage Formula
Percentage = (Part / Whole) × 100
Common Percentage Calculations
- X% of Y: (X/100) × Y — e.g., 15% of 200 = 30
- Percentage change: ((New − Old) / |Old|) × 100
- Percentage increase: ((New − Old) / Old) × 100 when New > Old
- Reverse percentage: If Y is X% of Z, then Z = Y / (X/100)
Frequently Asked Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 20% of 150 = (20/100) × 150 = 30.
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 is what percentage of 150? (30/150) × 100 = 20%.