How to use the Percentage Calculator
Enter the number and the percentage you want of it. The result is shown instantly, so you can change either value and compare.
Worked examples
15% of 80 is 80 × 15 ÷ 100 = 12. A 20% tip on a $45 bill is $9. To get 10% of anything, move the decimal point one place to the left: 10% of 250 is 25. From there, 5% is half of that and 20% is double.
Three different percentage questions
People often mix up three questions. What is 15% of 80? That is this calculator. What percentage is 12 of 80? That is the percentage of total calculator. How much did a price change from 80 to 92 in percent? That is the percentage change calculator. Picking the right one avoids most percentage mistakes.
What a percentage really is
A percentage is a way of expressing a number as a fraction of 100. 25% means 25 out of every 100, which is the same as the fraction 25/100 or the decimal form 0.25. That is why the percentage formula is simply value × percent ÷ 100: you turn the percent into a decimal and multiply. 40% of 60 is 0.4 × 60 = 24.
When the value has increased or decreased
To add a percentage, multiply by 1 plus the decimal. A $50 price increased by 8% is 50 × 1.08 = $54. To take a percentage away, multiply by 1 minus the decimal, so 50 decreased by 8% is 50 × 0.92 = $46. If you want to know the percent change between two numbers instead, use the percentage change calculator.
The formula
result = value × percent ÷ 100
Examples
- 15% of 250
37.5 (15% of 250)
- 8.5% sales tax on 80
6.8 (8.5% of 80)
- 120% of 50
60 (120% of 50)
Limitations and assumptions
Calculates a percentage of a number. To compare two values, use the percentage change or percentage of total calculators.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. 15% of 250 is 250 × 15 ÷ 100 = 37.5.
How do I find 10 percent quickly?
Move the decimal point one place left. 10% of 250 is 25.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. Use the percentage of total calculator for this.
How do I work out a percentage increase?
Use the percentage increase calculator: (new − old) ÷ old × 100.