Percentage Calculator
Work out any everyday percentage: a share of a number, what percent one number is of another, or how much something went up or down.
| 20% of 150 | 30 |
|---|
How to use it
- Pick the question you are asking from the list.
- Type the two numbers. The answer updates as you type.
- For a price increase or decrease, use "Percent change" with the old value as A and the new value as B.
Formula
A% of B = A ÷ 100 × BA as a percent of B = A ÷ B × 100Percent change = (B − A) ÷ |A| × 100
Example
A $150 jacket is 20% off. 20% of 150 = 0.20 × 150 = 30, so you save $30 and pay $120. If the price later rises from $120 back to $150, that is a (150 − 120) ÷ 120 × 100 = 25% increase, not 20%, because the starting value changed.
Questions
Why isn't a 20% drop undone by a 20% rise?
Each percentage is taken of a different starting value. Dropping 100 by 20% gives 80; raising 80 by 20% gives 96. To get back to 100 you need a 25% rise.
How do I calculate a percentage in my head?
Find 10% by moving the decimal one place left, then scale it. 15% of 60: 10% is 6, 5% is 3, so 15% is 9.
What is the difference between percent change and percent difference?
Percent change has a direction (old to new). Percent difference compares two values with no order, dividing by their average. Use the percent difference calculator for that.
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Last reviewed 2026-10-10. Found a mistake? Tell us.