Percentage Calculators
Eight percentage tools covering every common calculation — from finding what 15% of a number is to tracking how much a value changed or working backwards with the reverse percentage tool. Results appear as you type — no calculation needed on your end.
What these percentage tools help you with
- Tips and commissions — find exactly what 18% of $47.50 is (answer: $8.55) without mental math
- Discounts and tax — work out a percentage of any price, e.g. 20% off $65 = $13 off, $52 final
- Year-over-year comparisons — measure how much revenue, traffic, or costs rose or fell as a percentage change
- Test scores and grades — convert raw marks to a percentage, or find what score equals 80% on a 45-question test
- Measurement error — express the gap between an estimated and actual value as a percentage (e.g. predicted 200, got 185 → 7.5% error)
- Original prices — reverse a percentage to recover the value before a discount or markup was applied
All percentage calculators
Each tool handles a distinct type of percentage question. Choose based on what you're starting with — a rate, a result, or two values to compare.
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Percentage Calculator
Calculate percentages quickly and easily.
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What is X% of Y?
Find out what any percentage of a number is instantly.
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X is What Percent of Y?
Find what percentage one number is of another.
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Percentage Increase Calculator
Calculate the percentage increase between two values.
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Percentage Decrease Calculator
Calculate the percentage decrease between two values.
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Percentage Change Calculator
Calculate the percentage change between two values.
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Percentage Difference Calculator
Find the percentage difference between two numbers.
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Reverse Percentage Calculator
Work backwards from a percentage to find the original value.
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Percentage Error Calculator
Calculate the percentage error between experimental and theoretical values.
All tools run instantly in your browser — no sign-up, no data stored.
Common questions
Not sure which tool to use? These answers cover the most common points of confusion.
What's the difference between percentage change and percentage difference?
Percentage change requires a clear “before” and “after” — for example, sales going from $400 to $500 is a 25% increase. Percentage difference has no direction — it just measures how far apart two values are, without implying one came first.
How do I find the original price before a discount?
Use the reverse percentage calculator. If a price is $85 after a 15% discount, divide $85 by 0.85 to get $100 — the original. The tool does this automatically.
Which tool works for tips, tax, and commissions?
What is X% of Y? covers all three — enter the rate and the base. For sales tax, the sales tax calculator also returns the tax-inclusive total in one step.