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How to use the Percentage Calculator
- 1Pick the calculator that matches your question.
- 2Type your two numbers; the answer appears as you type.
- 3Click the result to copy it.
Percentage formulas
X% of Y = (X ÷ 100) × Y. For example, 20% of 150 = 30.
X is what percent of Y = (X ÷ Y) × 100. For example, 30 is 20% of 150.
Percentage change from X to Y = ((Y − X) ÷ |X|) × 100. Going from 80 to 100 is a 25% increase; going from 100 to 80 is a 20% decrease.
Quick percentage examples
| Question | Calculation | Answer |
|---|---|---|
| What is 15% of 80? | 0.15 × 80 | 12 |
| 30 is what % of 120? | 30 ÷ 120 × 100 | 25% |
| From 50 to 65? | (65 − 50) ÷ 50 × 100 | +30% |
| From 80 to 60? | (60 − 80) ÷ 80 × 100 | −25% |
| $60 after 25% off? | 60 × (1 − 0.25) | $45 |
Frequently asked questions
How do I calculate a discount?
Use 'What is X% of Y' with the discount percentage and the original price, then subtract the result from the price. A 25% discount on $80 is $20 off, so you pay $60.
Why is a 50% drop followed by a 50% gain not break-even?
Percentages are relative to the starting value. $100 down 50% is $50; $50 up 50% is only $75.