A percentage is a number out of 100. To find P% of a number, divide P by 100 and multiply: 20% of 150 is 0.20 × 150 = 30. To find what percent X is of Y, divide X by Y and multiply by 100.
New to percentages? Learn how to calculate percentage step by step, or print the percentage chart.
Percentage formulas
| Question | Formula | Example |
|---|---|---|
| What is P% of X? | P ÷ 100 × X | 20% of 150 = 30 |
| X is what % of Y? | X ÷ Y × 100 | 30 of 150 = 20% |
| X is P% of what? | X ÷ (P ÷ 100) | 30 is 20% of 150 |
| % change from A to B | (B − A) ÷ |A| × 100 | 150 → 180 = +20% Percentage change calculator → |
| A plus or minus P% | A × (1 ± P ÷ 100) | 150 − 20% = 120 Percentage increase calculator → |
Everyday examples
Discount: 25% off a price of 80 → you pay 60
Percent off calculator →Test score: 42 out of 50 → 84%
Marks percentage calculator →Rent: from 1,200 to 1,290 → +7.5%
Percentage change calculator →Common mistakes
- +20% then −20% doesn’t get you back: 100 → 120 → 96.
- Percent vs. percentage points: going from 5% to 7% is +2 points, but a 40% increase.
- Averaging percentages with different totals gives the wrong answer. Average percentage calculator →
Percentages in Excel and Google Sheets
- Percent of total, then format the cell as %
=A2/B2 - Percent change
=(B2-A2)/A2
All percentage calculators
FAQ
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. 15% of 80 is 15 ÷ 100 × 80 = 12.
How do I calculate a percentage on a regular calculator?
Type the number, press ×, type the percentage and press %. On most calculators 80 × 15 % shows 12. If yours has no % key, multiply by the percentage and divide by 100.
How do I add 20% to a price?
Multiply the price by 1.2: 50 × 1.2 = 60. To take 20% off instead, multiply by 0.8.
What’s the difference between percent and percentage points?
Percentage points measure the gap between two percentages; percent measures a relative change. Going from 5% to 7% is 2 percentage points, but a 40% increase.
Are my numbers stored anywhere?
No. The calculation runs in your browser and nothing you type is sent to a server. Recent calculations stay on your device, and you can clear them from the ⋯ menu.
How we calculate: exact decimal math (no rounding errors), you choose the decimal places, and your numbers never leave your browser. Methodology →
Updated October 2026Free printable percentage charts and worksheets with answer keys
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