Percentage Calculator
Work out percentages, increases, decreases and what percent one number is of another.
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What is X% of Y?
Result
36
X is what percent of Y?
Result
15%
Percentage increase or decrease
Increase of
25%
Results update as you type.
How percentages are calculated
A percentage is just a fraction written out of one hundred. Every calculation on this page comes from one of three arrangements of the same relationship.
Part = (Percent / 100) x Whole
Percent = (Part / Whole) x 100
Change = ((New - Old) / Old) x 100
The third formula is the one people most often get wrong, because the divisor is always the original value. Comparing against the new value instead gives a different and usually smaller figure, which is why a rise and a fall of the same percentage do not cancel each other out.
Frequently asked questions
How do I work out a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 240 is (15 / 100) x 240 = 36. The first calculator above does this for you as you type.
What is the difference between percentage change and percentage difference?
Percentage change compares a new value against an original one and has a direction — it can be an increase or a decrease. Percentage difference compares two values without treating either as the starting point, and is always positive.
Why does a 50% increase followed by a 50% decrease not return the original number?
Because each percentage applies to a different base. Increasing 100 by 50% gives 150, and decreasing 150 by 50% removes 75, leaving 75. The second percentage is taken from the larger number, so the two do not cancel out.
How do I reverse a percentage to find the original price?
Divide by one plus the rate as a decimal. If a price of 118 already includes 18% tax, the pre-tax figure is 118 / 1.18 = 100. Use the third calculator and read the change in reverse, or divide directly.
Is anything I type here sent anywhere?
No. The whole calculation runs in your browser using JavaScript. Nothing is uploaded, stored or logged, and the tool keeps working if you go offline after the page has loaded.