Calculate any percentage — what is X% of Y, X is what % of Y, increase by %, discount, and percentage change between two numbers
Result
Enter values above to see the result
X% of Y
Result = (X / 100) × Y
X is ?% of Y
% = (X / Y) × 100
% Change
% = ((New − Old) / Old) × 100
Add %
Result = Y × (1 + X/100)
Discount
Final = Price × (1 − %/100)
Reverse %
Original = Result / (1 ± %/100)
About This Tool
Percentages come up everywhere — shopping discounts, tax calculations, tips, grades, salary raises, data analysis. But the mental math gets tricky fast. What's 17.5% of 249? If something went from 80 to 95, what's the percentage increase?
This calculator handles every common percentage operation in one place. Six modes cover everything from basic "what is X% of Y" to percentage change between two values and discount calculations. Enter your numbers and get instant results with the formula shown so you understand the math.
No need to remember which number goes where or whether to multiply or divide — just pick the mode that matches your question and fill in what you know.
How to Use
1. Choose the calculation mode that matches your question
2. Enter the known values
3. See the result instantly with the formula used
4. Use "Copy Link" to share a specific calculation
Formula
X% of Y = (X / 100) × Y
X is what % of Y = (X / Y) × 100
Increase: Y × (1 + X/100)
Decrease: Y × (1 − X/100)
% Change = ((New − Old) / Old) × 100
Discount: Price × (1 − Discount/100)
Frequently Asked Questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 200 = (15/100) × 200 = 0.15 × 200 = 30. To find 8.5% of 450: (8.5/100) × 450 = 38.25.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 is what percent of 200? (30/200) × 100 = 15%. Or: 45 out of 60 = (45/60) × 100 = 75%.
How do I calculate percentage increase?
Subtract the old value from the new value, divide by the old value, and multiply by 100. From 80 to 100: ((100 − 80) / 80) × 100 = 25% increase. A salary going from $50,000 to $55,000 is a 10% increase.
How do I calculate a discount?
Multiply the original price by (1 − discount/100). A $80 item with 25% off: $80 × (1 − 0.25) = $80 × 0.75 = $60. You save $20. Or simply: $80 × 0.25 = $20 off, then $80 − $20 = $60.
How do I add a percentage to a number?
Multiply the number by (1 + percentage/100). To add 15% to 200: 200 × 1.15 = 230. This works for tax, tips, markups, and raises. To add 8.875% sales tax to $50: $50 × 1.08875 = $54.44.
What is the difference between percentage and percentage points?
A percentage is relative, while percentage points are absolute. If a rate goes from 10% to 15%, it increased by 5 percentage points but by 50% (because 5 is 50% of 10). This distinction matters in finance, statistics, and reporting.
How do I reverse a percentage?
To find the original number before a percentage was applied, divide by (1 + rate/100) for increases or (1 − rate/100) for decreases. If a price after 20% markup is $60, the original was $60 / 1.20 = $50. If a sale price after 30% off is $35, the original was $35 / 0.70 = $50.