Percentage Calculator
This free percentage calculator handles every common percentage question in one place: finding a percentage of a number, working out what percent one number is of another, finding the original total, and calculating a percentage increase or decrease.
Pick a calculation type below, type in your numbers, and the percentage calculator updates the answer instantly — no button to press, and no sign-up required.
What is X% of Y? — e.g. what is 20% of 150.
X is what percent of Y? — e.g. 30 is what percent of 150.
X is P% of what number? — e.g. 20 is 25% of what number.
What's the percentage change from X to Y? — e.g. from 80 to 100.
Your last calculations
Change any field and a calculation will be saved here automatically.
How to use this percentage calculator
Choose a calculation type
Percentage of a number, what percent, find the total, or percentage change.
Enter your numbers
Type the two numbers the calculation needs.
Read the result
The answer updates instantly as you type — no button needed.
Copy, print or share it
And it's automatically saved to your calculation history.
The percentage formulas behind each calculation
Every percentage calculator ultimately runs on the same core formula — here's how each calculation type uses it.
Percentage of a number
(percentage ÷ 100) × number
Used for tips, discounts, and any "X% of Y" question.
What percent one number is of another
(part ÷ whole) × 100
The core percentage formula — this is what the other three build on.
Finding the total from a percentage
part ÷ (percentage ÷ 100)
Useful when you know a portion and its percentage, but not the whole.
Percentage increase or decrease
((new − old) ÷ old) × 100
A positive answer is an increase; a negative answer is a decrease.
Common percentage calculations
A few percentages of round numbers, worked out for quick reference.
| Percentage | Of 50 | Of 100 | Of 200 | Of 500 |
|---|---|---|---|---|
| 10% | 5 | 10 | 20 | 50 |
| 15% | 7.5 | 15 | 30 | 75 |
| 20% | 10 | 20 | 40 | 100 |
| 25% | 12.5 | 25 | 50 | 125 |
| 50% | 25 | 50 | 100 | 250 |
Percentage calculator: frequently asked questions
What is the basic percentage formula?
The basic percentage formula is (part ÷ whole) × 100. This tells you what percentage the part is of the whole. This percentage calculator uses that formula, and its reverse, for every calculation type above.
How do I calculate a percentage of a number?
Multiply the number by the percentage, then divide by 100. For example, 20% of 150 is (20 × 150) ÷ 100, which equals 30.
How do I calculate percentage increase or decrease?
Subtract the old value from the new value, divide by the old value, then multiply by 100. A positive result is a percentage increase, and a negative result is a percentage decrease.
How do I find the original number from a percentage?
Divide the known part by the percentage (as a decimal). For example, if 20 is 25% of a number, the number is 20 ÷ 0.25, which equals 80.
What's the difference between percentage points and percent?
Percentage points measure the raw difference between two percentages, while percent measures relative change. Going from 20% to 25% is a rise of 5 percentage points, but a 25% relative increase.
Is this percentage calculator free to use?
Yes. This percentage calculator is completely free, with no sign-up required, and every calculation happens instantly in your browser.
Related reading
Percentage points vs percent, explained
Why "up 5 points" and "up 5%" aren't the same thing.
Read article →Working out a tip percentage fast
Quick mental-maths shortcuts for common tip percentages.
Read article →Percentage change vs percentage difference
Two calculations that sound similar but answer different questions.
Read article →Results are rounded for readability. For financial, tax, or academic calculations that need exact figures, double-check the result against your own working.