Four separate calculators for the four questions people actually ask about percentages.
What is X% of Y?
X is what percentage of Y?
Percentage increase or decrease
Percentage difference between two values
What the percentage calculator does
Percentages trip people up because one word covers several different sums. Working out a tip is not the same operation as working out how much a price rose, and percentage change is not the same as percentage difference. Each calculator here handles one question and writes the answer out as a sentence so you can check it says what you meant.
Answers update as you type and are rounded to six decimal places.
How to use it
- Pick the question that matches yours. Scroll to the calculator whose heading describes what you are working out.
- Fill in both boxes. Decimals and negative numbers are fine. The answer appears underneath immediately.
- Read the sentence, not just the number. Each result restates your inputs so you can confirm you entered them the right way round.
Features
- Percent of a number, for tips, tax, commission and discounts
- One number as a percentage of another, for scores and shares
- Percentage increase and decrease between two values
- Percentage difference relative to the average of two values
- Results written as full sentences
- Clear handling of zero, which has no meaningful percentage change
Common uses
- Adding a tip or working out sales tax
- Checking a discount before you pay
- Turning a test score into a percentage
- Comparing this month's revenue with last month's
- Expressing the gap between two measurements in a report
How your data is handled
The arithmetic happens in your browser. Nothing you type is sent to a server.
Frequently asked questions
How do I calculate a percentage of a number by hand?
Divide the percentage by 100 and multiply by the number. For 15% of 240: 15 ÷ 100 = 0.15, then 0.15 × 240 = 36.
What is the difference between percentage change and percentage difference?
Percentage change has a direction: it measures movement from a starting value to an ending value, so the starting value is the reference point. Percentage difference is symmetric and compares two values against their average, which is what you want when neither value came first.
Why does a 20% rise followed by a 20% fall not return the original number?
Each percentage applies to a different base. 100 rises by 20 to 120, then 20% of 120 is 24, leaving 96. Percentages always refer to the value they are applied to.
How do I remove a percentage that has already been added?
Divide rather than subtract. To strip 20% tax from 120, divide by 1.20 to get 100. Subtracting 20% of 120 would leave 96, which is wrong.
What are percentage points?
They are the plain arithmetic gap between two percentages. A rate moving from 4% to 6% rose by 2 percentage points, which is a 50% increase in the rate itself.
Can I use negative numbers?
Yes. Percentage change from a negative starting value is measured against its absolute size, which keeps the direction of the change correct.