How to Calculate a Percentage
A percentage is a way of expressing a number as a fraction of 100. The word "percent" literally means "per hundred." There are four common percentage calculations — all handled by this calculator.
Common Percentage Reference Table
Here are the most frequently needed percentage calculations for quick reference:
| Percentage | Of 100 | Of 200 | Of 500 | Of 1,000 |
|---|---|---|---|---|
| 5% | 5 | 10 | 25 | 50 |
| 10% | 10 | 20 | 50 | 100 |
| 15% | 15 | 30 | 75 | 150 |
| 20% | 20 | 40 | 100 | 200 |
| 25% | 25 | 50 | 125 | 250 |
| 50% | 50 | 100 | 250 | 500 |
| 75% | 75 | 150 | 375 | 750 |
Everyday Uses for Percentage Calculations
Quick Mental Percentage Tricks
These shortcuts make percentage calculations faster without a calculator:
- 10% of any number — move the decimal point one place to the left. 10% of 340 = 34
- 5% of any number — find 10% and halve it. 5% of 340 = 17
- 20% of any number — find 10% and double it. 20% of 340 = 68
- 25% of any number — divide by 4. 25% of 340 = 85
- 50% of any number — divide by 2. 50% of 340 = 170
- Reverse percentages — X% of Y = Y% of X. So 8% of 25 = 25% of 8 = 2
FAQs
How do I calculate a percentage?
Divide the part by the whole and multiply by 100. For example, 45 out of 60 is (45 ÷ 60) × 100 = 75%.
How do I calculate a percentage increase?
Subtract the original value from the new value, divide by the original, then multiply by 100. For example, 80 to 100 is ((100 − 80) ÷ 80) × 100 = 25% increase.
What is 20% of a number?
Divide the number by 5. For example, 20% of 150 = 150 ÷ 5 = 30. Or use the calculator above for any amount instantly.
How do I work out what percentage one number is of another?
Divide the first number by the second and multiply by 100. For example, 30 is what percentage of 150? (30 ÷ 150) × 100 = 20%.
What is the difference between percentage increase and percentage decrease?
A percentage increase measures how much a value has grown relative to the original. A percentage decrease measures how much it has fallen. Both use the original value as the reference point.
Is this calculator free?
Yes — completely free, no sign-up required.