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Percentage calculator
Reference table
| Value | 5% | 10% | 15% | 20% | 25% | 50% |
|---|---|---|---|---|---|---|
| 50 | 2.5 | 5 | 7.5 | 10 | 12.5 | 25 |
| 100 | 5 | 10 | 15 | 20 | 25 | 50 |
| 150 | 7.5 | 15 | 22.5 | 30 | 37.5 | 75 |
| 200 | 10 | 20 | 30 | 40 | 50 | 100 |
| 500 | 25 | 50 | 75 | 100 | 125 | 250 |
| 1,000 | 50 | 100 | 150 | 200 | 250 | 500 |
Formulas
X% of Y = (X ÷ 100) × Y · X as % of Y = (X ÷ Y) × 100 · % change = (new − old) ÷ |old| × 100
Worked example: 15% of 200 = (15 ÷ 100) × 200 = 30. And 30 is (30 ÷ 200) × 100 = 15% of 200. The two operations are inverses.
The three most common mistakes
1. Percent change is not percentage points. If a rate goes from 10% to 15% it rose 5 percentage points, but the change is 50%. 2. Consecutive increases and discounts do not add up. +10% then −10% does not return to the original: 100 → 110 → 99. 3. Reverse percentages. A product that rose 25% needs to drop 20% (not 25%) to return to its original price, because the base changed.
Last updated: · Methodology and sources