Percentage Calculator
Results appear as you type. Just fill in the line you need.
1. What is X% of a number?
2. A is what percent of B?
3. Percentage increase or decrease
4. Price after a discount or markup
Percentage formulas at a glance
| You want | Formula | Example |
|---|---|---|
| B% of A | A x B / 100 | 15% of 200 = 30 |
| A as a % of B | A / B x 100 | 12 is 24% of 50 |
| Percent change | (new - old) / old x 100 | 800 to 1,000 = 25% increase |
| Sale price | A x (1 - B / 100) | 50 with 30% off = 35 |
| Original price (reverse) | sale price / (1 - B / 100) | 35 after 30% off was 50 |
Every calculation here is a ratio against 100. The most common mistake is using the wrong base: a percentage change is always measured against the starting value, which is why a 50% drop needs a 100% rise to get back to where you were. For sales tax and VAT, try the VAT calculator, and for business pricing see the margin calculator.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 15% of 200 is 200 x 15 / 100 = 30. To find what percent one number is of another, divide the part by the whole and multiply by 100: 12 out of 50 is 12 / 50 x 100 = 24%.
How do I work out percentage increase or decrease?
Use (new value - old value) / old value x 100. If sales go from 800 to 1,000, that is (1,000 - 800) / 800 x 100 = a 25% increase. Going back from 1,000 to 800 is only a 20% decrease, because the starting point is different.
What is the difference between percent and percentage points?
Percentage points are the plain difference between two percentages. If an interest rate rises from 3% to 4%, it went up 1 percentage point, but in relative terms it rose (4 - 3) / 3 = about 33%. News reports on interest rates and polls usually talk in percentage points.
Is 30% off and then another 20% off the same as 50% off?
No. The second discount applies to the already reduced price, so you pay 0.7 x 0.8 = 0.56 of the original, which is a 44% discount in total. You can check it by running the discount calculator below twice.