Percentage Calculator
Work out a percentage of a number, what percent one number is of another, the percent change between two numbers, and prices before or after a discount or markup.
Percent of a number
What percent one number is of another
Percentage change (increase or decrease)
Add a percentage (markup, tax, raise)
Take off a percentage (discount)
Original price before a discount
Original number before an increase
How the results are calculated
- X% of Y = Y × X ÷ 100. A as a percent of B = A ÷ B × 100. Change from A to B = (B − A) ÷ |A| × 100. Y after +X% = Y × (1 + X ÷ 100); before it = Y ÷ (1 + X ÷ 100).
- Numbers are calculated exactly, as fractions, and only rounded to the decimal places you choose when they are shown.
- A change between two percentages can also be given in percentage points: from 4% to 5% is 1 percentage point, or a 25% increase.
- Everything runs in your browser. The numbers you enter are not sent to LeedyBox or saved.
Wrong result? If a result looks wrong, email us the numbers you entered and the result you expected, so we can fix it.
Does a sentence on this page sound unnatural in your language? Let us know that too.
How to use
- Pick the card for your question, such as "Percent of a number" or "Take off a percentage (discount)".
- Type the two numbers. Decimals work with the decimal mark of your language, and you can paste numbers with thousands separators.
- The result appears under the card as you type. Change "Decimal places" to round it differently; "(rounded)" shows when the exact result has more decimals.
- To check a discount, use "Take off a percentage"; to find the price before a sale, use "Original price before a discount".
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. 15% of 80 is 80 × 15 ÷ 100 = 12.
How do I work out percentage increase or decrease?
Subtract the old value from the new one, divide by the old value and multiply by 100. From 80 to 100: (100 − 80) ÷ 80 × 100 = 25% increase. From 100 to 80 it is a 20% decrease, because the change is measured against the starting value.
How do I find the original price before a discount?
Divide the sale price by (1 − discount ÷ 100). A price of 60 after 25% off was 60 ÷ 0.75 = 80. Taking 25% of 60 and adding it back gives 75, which is wrong.
Why does +10% and then −10% not give the starting number?
The second percentage is taken from a different number. 100 + 10% = 110, and 110 − 10% = 99. To undo a 10% increase, divide by 1.1 instead.
What is the difference between percent and percentage points?
Percentage points are the plain difference between two percentages: a rate going from 4% to 5% rises by 1 percentage point. As a percent change of the rate itself, that is a 25% increase.
Is what I enter sent anywhere?
No. The calculations run in your browser, and the page does not save the numbers you enter.