- 100% free
- No sign-up
- Runs in your browser
Percentage Calculator
Work out percentages, percentage change, and increases or decreases — answers update as you type.
What is X% of Y?
Formula: X ÷ 100 × Y
X is what percent of Y?
Formula: X ÷ Y × 100
Percentage change from X to Y
Formula: (Y − X) ÷ |X| × 100 — positive is an increase, negative a decrease
Increase Y by X%
Formula: Y × (1 + X ÷ 100)
Decrease Y by X%
Formula: Y × (1 − X ÷ 100)
About Percentage Calculator
Percentage Calculator answers the five percentage questions people ask most: what X% of a number is, what percentage one number is of another, the percentage change between two values, and the result of increasing or decreasing a number by a percentage. Each answer updates as you type, with the formula shown underneath.
Shopping is the everyday case. A 25% discount on Rs 4,800, the price after a 17% sales tax, or whether “save Rs 900” is a bigger deal than “15% off” are all one line here. The same arithmetic drives tips and service charges, commission, and splitting a bill fairly.
Percentage change is the one most often done wrong. Going from 80 to 100 is a 25% increase, but going back from 100 to 80 is a 20% decrease, because the change is always measured against the starting value. The calculator uses that rule and shows the sign, so a fall reads as negative.
Students use it to turn marks into percentages, businesses to compare month-on-month sales, and investors to check returns. Seeing the formula next to each answer makes it easy to check the working or repeat it in a spreadsheet.
How to calculate percentages
- Find the question that matches what you want to know.
- Type the two numbers into that row.
- Read the answer immediately to the right.
- Check the formula underneath if you want to verify it.
Tips & common problems
Change is measured from the start
Percentage change divides by the original value. That is why +25% and −20% can describe the same two numbers in opposite directions.
Two discounts do not add up
20% off and then another 10% off is 28% off in total, not 30% — the second discount applies to the already-reduced price. Use the decrease row twice to see it.
Adding and removing tax are different
Adding 17% then taking 17% off does not return the original price. To strip tax from a total, divide by 1.17 instead.
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 is 0.15 × 200 = 30.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 45 out of 60 is 45 ÷ 60 × 100 = 75%.
How is percentage change calculated?
Subtract the old value from the new one, divide by the old value, and multiply by 100. A negative result is a decrease.
How do I work out a price after a discount?
Use the “Decrease Y by X%” row: enter the discount percentage and the original price.
Can I use decimals and negative numbers?
Yes. Decimals work everywhere, and negative numbers are handled correctly in percentage change.