Percentage Calculator
Work out percentages the easy way — find a percentage of a number, what percent one value is of another, or the percentage change between two numbers. Everything updates instantly in your browser.
What is X% of Y?
X is what percent of Y?
Percentage change from X to Y
How to calculate a percentage
A percentage is just a fraction of 100. To find a percentage of a number, convert the percent to a decimal (divide by 100) and multiply. For example, 15% of 200 is 0.15 × 200 = 30. To find what percent one number is of another, divide the first by the second and multiply by 100: 30 ÷ 150 × 100 = 20%.
Percentage increase and decrease
To find the percentage change between two values, subtract the old from the new, divide by the old, and multiply by 100. Going from 80 to 100 is (100 − 80) ÷ 80 × 100 = 25% increase. A negative result means a decrease. This is the formula behind price changes, growth rates, and discounts.
Everyday uses
- Shopping: work out a sale price — 30% off $80 is $56.
- Tips & tax: add 18% to a bill, or find the tax portion.
- Grades & scores: convert marks to a percentage.
- Finance: calculate interest, returns, or how much a value grew.
Fast and private
Every calculation runs in your browser as you type — nothing is uploaded, and it works offline once loaded. No signup, no limits, just the answer.
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Frequently asked questions
How do I find 20% of a number?
Multiply the number by 0.20. For example, 20% of 150 is 150 × 0.20 = 30. Or use the first calculator above.
How do I calculate percentage increase?
Subtract the old value from the new value, divide by the old value, then multiply by 100. From 80 to 100 is a 25% increase.
Is my data uploaded?
No. All math runs locally in your browser; nothing you enter is sent anywhere.