Percentage Calculator
Calculate percentages three different ways.
Percentages appear everywhere — discounts, tax rates, test scores, growth metrics, investment returns, and nutritional labels. This calculator handles the three most common percentage operations: finding a percentage of a number, determining what percentage one number is of another, and calculating percentage increase or decrease.
What is % of ?
is what % of ?
Percentage change from to
How to Use the Percentage Calculator
- Calculator 1 — Enter a percentage and a number to find that percentage of the number (e.g., 15% of 200 = 30).
- Calculator 2 — Enter two numbers to find what percentage the first is of the second (e.g., 30 is 15% of 200).
- Calculator 3 — Enter a starting and ending value to find the percentage change (increase or decrease).
- Click Calculate — each section has its own calculate button. The answer appears instantly below.
Every Percentage Formula, With Examples
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | Y × X ÷ 100 | 15% of 80 = 80 × 15 ÷ 100 = 12 |
| X is what % of Y? | X ÷ Y × 100 | 12 is what % of 80? → 12 ÷ 80 × 100 = 15% |
| % change from A to B | (B − A) ÷ A × 100 | 40 → 52: (52−40) ÷ 40 × 100 = +30% |
| Increase Y by X% | Y × (1 + X ÷ 100) | 80 + 15% = 80 × 1.15 = 92 |
| Decrease Y by X% | Y × (1 − X ÷ 100) | 80 − 15% = 80 × 0.85 = 68 |
| Reverse: before an X% increase | Y ÷ (1 + X ÷ 100) | 92 after +15% → 92 ÷ 1.15 = 80 |
The reverse formula is the one people get wrong most often: to undo a 15% increase you divide by 1.15 — you do not subtract 15%, because the 15% was applied to the smaller original number. A €92 price that includes a 15% markup was €80, not €78.20.
Real-World Worked Examples
- Discount: a $65 jacket at 30% off → 65 × 0.70 = $45.50.
- VAT/sales tax: 20 net + 18% tax → 120 × 1.18 =41.60; the tax portion is $21.60.
- Price with tax, tax unknown:
41.60 including 18% → 141.60 ÷ 1.18 =20 net.- Test score: 42 of 56 questions correct → 42 ÷ 56 × 100 = 75%.
- Salary raise: $54,000 → $58,320 is (58,320 − 54,000) ÷ 54,000 × 100 = +8%.
Frequently Asked Questions
How do I calculate a percentage of a number? ▼To find X% of Y, multiply Y by X then divide by 100. For example, 15% of 200 = 200 × 15 / 100 = 30. Use Calculator 1 above — just enter 15 and 200, then click Calculate.How do I find what percentage one number is of another? ▼Divide the part by the whole and multiply by 100. For example: 30 is what percent of 200? → 30 / 200 × 100 = 15%. Use Calculator 2 above for this.How do I calculate percentage increase? ▼Percentage increase = ((New Value − Old Value) / |Old Value|) × 100. For example, from 100 to 150 is a 50% increase. Use Calculator 3 above — enter 100 and 150 to get +50%.How do I calculate a discount? ▼To find the sale price: Sale Price = Original Price × (1 − Discount% / 100). For a 20% discount on a £80 item: £80 × (1 − 0.20) = £64. Alternatively, use Calculator 1 to find 20% of 80, then subtract from 80.What is the difference between percentage point and percent change? ▼A percentage point is the arithmetic difference between two percentages — going from 10% to 15% is +5 percentage points. Percent change is relative — 10% to 15% is a 50% increase (5/10 × 100). These are often confused in news reporting.📖 Further reading: How to Calculate Percentages: Formulas, Tips, and Examples
- Price with tax, tax unknown: