What is X% of Y?
% of
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X is what % of Y?
is what % of
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Percentage change from X to Y
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Tip calculator
–Tip
–Total
–Per person
How to use the Percentage Calculator
Fill in any field in a block, results update automatically as you type. Use the tip calculator to split a restaurant bill with any tip percentage.
The four calculation modes
- What is X% of Y?: find a percentage of a number. Example: What is 15% of 80? → 12. Use this for discounts, tax amounts, and tip calculations.
- X is what % of Y?: find what percentage one number is of another. Example: 12 is what % of 80? → 15%. Use this to compare scores, proportions, and shares.
- % change from X to Y: find the percentage increase or decrease. Example: from 80 to 92 = +15%. Negative values indicate a decrease.
- Tip calculator: calculate a tip on a bill and split it equally among any number of people.
Common percentage formulas
| Problem | Formula |
|---|---|
| X% of Y | (X / 100) × Y |
| X is what % of Y? | (X / Y) × 100 |
| % change from A to B | ((B − A) / A) × 100 |
| Value after X% increase | Value × (1 + X/100) |
| Value after X% decrease | Value × (1 − X/100) |
| Original price before X% discount | Sale price / (1 − X/100) |
Practical examples
- VAT / sales tax: a €100 item with 20% VAT: 20% of 100 = €20, total = €120
- Discount: a €120 item at 25% off: 25% of 120 = €30, discounted price = €90
- Grade percentage: 42 correct out of 56 questions: 42 is what % of 56 = 75%
- Salary increase: from €2,800 to €3,080: % change = +10%