Percentage Calculator
Calculate percentages instantly. Choose a mode: find X% of a number, determine what percent one number is of another, or compute the percentage change between two values.
% of=70
Result
70
Formula
20% × 350 = 70
Frequently Asked Questions
How do I calculate what percentage X is of Y?
Divide X by Y and multiply by 100. For example, 25 is what percent of 200? (25 ÷ 200) × 100 = 12.5%.
How do I calculate X% of a number?
Multiply the number by X and divide by 100. For example, 15% of 80 = (80 × 15) ÷ 100 = 12.
How do I calculate percentage change?
Subtract the old value from the new value, divide by the old value, then multiply by 100. A positive result means increase; negative means decrease.
What is the formula for percentage increase?
Percentage increase = ((New Value − Old Value) ÷ Old Value) × 100. For example, from 50 to 75: ((75 − 50) ÷ 50) × 100 = 50% increase.
The Three Core Percentage Formulas
| Question | Formula | Example |
|---|---|---|
| What is X% of N? | Result = N × X / 100 | 15% of 80 = 12 |
| X is what % of N? | Result = (X / N) × 100 | 12 is 15% of 80 |
| % change from A to B? | ((B − A) / A) × 100 | 50 to 75 = +50% |
Everyday Use Cases
- Discounts — a 20% discount on a $85 item: 85 × 20 / 100 = $17 off → final price $68.
- Tax — sales tax of 8.5% on $120: 120 × 8.5 / 100 = $10.20 tax → total $130.20.
- Grade calculation — scored 42 out of 55 points: (42 / 55) × 100 = 76.4%.
- Growth rate — monthly active users grew from 10,000 to 13,500: ((13500 − 10000) / 10000) × 100 = +35%.