Percentage Calculator
Free percentage calculator: find X% of Y, calculate percent change, increase/decrease, and add or subtract a percentage from any number. Instant results.
Updated April 2026
What is X% of Y?
Formula
Result = (X ÷ 100) × Y
e.g. What is 20% of 500? → (20 ÷ 100) × 500 = 100
X is what % of Y?
Percentage = (X ÷ Y) × 100
e.g. 50 is what % of 200? → (50 ÷ 200) × 100 = 25%
Percentage increase or decrease from X to Y
% Change = ((Y − X) ÷ |X|) × 100
e.g. From 80 to 100 → ((100 − 80) ÷ 80) × 100 = 25% increase
Value X with Y% added or subtracted
New value = X × (1 + Y ÷ 100)
e.g. 1000 + 15% → 1000 × 1.15 = 1,150
How to use the percentage calculator
Four calculators, one instant result — with the formula shown every time
1. Pick the calculation you need
Four sections cover the most common percentage problems — find the one that matches your question.
2. Enter your numbers
The result updates instantly as you type, with no submit button or page reload.
3. Copy the result
One click copies the answer to your clipboard and saves the calculation to your history.
What this percentage calculator does
Four calculations that cover almost every question — from percent of a number to percentage increase and decrease
What is X% of Y?
For discounts, tips, sales tax, and commissions.
X is what % of Y?
For test scores, market share, and response rates.
Percentage increase or decrease
Salary raises, price changes, revenue growth between two values.
Add or subtract a percentage
Apply a discount, add sales tax, or work out a price after a markup.
Examples
Real inputs and the exact result each one produces
When you'll use this
The most common reasons people reach for a percentage calculator
Calculate a discount or tax
"30% off $80" or "8% sales tax on $500" — get the exact amount instantly.
Check a test score
"I got 72 out of 90 — what percentage is that?" The answer: 80%.
Compare a raise or price change
Enter the old and new value to find the exact percentage increase or decrease.
Apply a markup or tax to a price
Add VAT, sales tax, or a service fee on top of a base price.
Common mistakes
Where percentage math usually goes wrong
Confusing percentage increase with percentage change
Percentage increase compares a new value to a fixed original. Percentage change (sometimes called percentage difference) averages both values and is always reported as positive.
Assuming a percentage can't go over 100%
Going from 50 to 150 is a 200% increase — this shows up constantly in revenue growth and investment returns, not just abstract math problems.
Using the wrong formula to reverse a discount
To find the price before a 30% discount, divide by 0.70 — multiplying by 1.30 gives the wrong number and is a common mistake.
Why use this percentage calculator
It combines the four percentage calculations that cover nearly every real-world situation — not just "what is X% of Y," but also the reverse question, the percentage change between two numbers, and applying a percentage to a value.
Every result shows the formula behind it, so you learn the calculation while solving the problem in front of you, and your last 20 calculations stay saved locally so you can check back on them.
The four calculations
Which one matches your question
Frequently asked questions
Divide the part by the whole, then multiply by 100. For 30 out of 120: (30÷120)×100 = 25%. This is the formula behind the "X is what % of Y" calculator above.
References
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