Invoice LuxeHow to Calculate a Percentage of a Number (Formula + Examples)
Learn how to calculate a percentage of a number, find what percent one number is of another and work out the total from a percentage. Simple formulas and a quick table.
Percentages appear in prices, discounts, tax, tips and invoices. Once you know three simple formulas, you can solve almost every percentage problem.
Percentage of a number = number × percentage ÷ 100
How do you calculate a percentage of a number?
Example: what is 15% of 240?
- Convert the percentage to a decimal: 15 ÷ 100 = 0.15
- Multiply: 240 × 0.15 = 36
So 15% of 240 is 36.
Want to try it right away? Percentage Calculator is free and needs no signup.
Quick table
| Percentage | Of 250 | Shortcut |
|---|---|---|
| 10% | 25 | Divide by 10 |
| 25% | 62.5 | Divide by 4 |
| 50% | 125 | Divide by 2 |
| 5% | 12.5 | Half of 10% |
| 20% | 50 | Double 10% |
What percent is one number of another?
Formula: part ÷ whole × 100.
Example: 45 is what percent of 180? 45 ÷ 180 = 0.25, and 0.25 × 100 = 25%.
How do you find the total when you know the percentage?
Formula: part ÷ percentage × 100.
Example: 30 is 12% of a number. 30 ÷ 12 × 100 = 250.
How do you add or subtract a percentage?
- Add 20%: multiply by 1.20. For example 80 × 1.20 = 96.
- Subtract 20%: multiply by 0.80. For example 80 × 0.80 = 64.
This is exactly how VAT and discounts work. See how to calculate discount percentage and how to calculate VAT.
Common percentage mistakes
- Forgetting to divide by 100. 15% is 0.15, not 15.
- Mixing up the part and the whole. The whole is the number you compare against.
- Adding and subtracting the same percent. +20% then −20% does not return to the start. See percentage increase and decrease.
Calculate any percentage instantly
Use the percentage calculator for percent of, percent change and increase or decrease, with no manual maths.
FAQ
What is 10 percent of a number?
Divide the number by 10. For 250, 10% is 25.
How do I calculate 20 percent of a price?
Multiply the price by 0.20, or find 10% and double it.
How do I turn a percentage into a decimal?
Divide by 100. For example 7.5% = 0.075.
What is the difference between a percentage and a percentage point?
If a rate goes from 4% to 6%, it rose by 2 percentage points, which is a 50% increase.