Percentage Calculator
Quickly calculate any percentage: what is X% of Y, X is what percent of Y, and percentage increase or decrease. Free and private.
Runs in your browser — nothing uploaded
What is X% of Y?
X% of Y is
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Use this free percentage calculator to answer three of the most common everyday questions: what is a percentage of a number, what percentage one number is of another, and how much something has gone up or down in percent. It is great for tips, taxes, discounts, grades, and quick sanity-check maths.
Private by design — your data never leaves your device
How to use it
No account, no upload — it all happens on your device.
1
Pick the mode that matches your question: % of, is what %, or % change.
2
Type the two numbers into the input fields. The calculator runs as you type.
3
Read the big result at the bottom — and the formula underneath so you can see how it was worked out.
4
Hit Copy to put the result on your clipboard.
The three percentage questions
Almost every percent problem reduces to one of these.
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | (X ÷ 100) × Y | 25% of 200 = 50 |
| X is what % of Y? | (X ÷ Y) × 100 | 30 is 60% of 50 |
| % change from A to B | ((B − A) ÷ A) × 100 | 40 → 50 is a 25% increase |
Everyday uses
Where the maths actually shows up.
- Tipping. A 20% tip on a $48 bill is 20% of 48 = $9.60.
- Sales tax. Add 8.875% to a $250 sticker price — total $272.19.
- Discounts. 30% off $89 is 30% of 89 = $26.70 off, paying $62.30.
- Grades. 47 out of 60 on a test is 47/60 × 100 = 78.3%.
- Stock moves. A share that went from $120 to $138 climbed 15%.
- Salary raises. Going from $72k to $78k is an 8.3% bump.
Pitfalls to watch for
- Percent of vs percent off."30% off $50" means you pay $35 (50 − 15). "30% of $50" is just $15. Read the question.
- Stacked percentages don't add. A 20% discount followed by another 10% discount is not30% off — it's 28% off (you multiply 0.8 × 0.9 = 0.72, so you pay 72%).
- Reverse percentage. If something is 20% off and costs $80, the original was not$96 — it was $100 (80 ÷ 0.8). Going up doesn't cancel going down.
- Percentage points vs percent. A poll going from 40% to 44% rose by 4 percentage points, but a 10% percentage increase. Both are right; they answer different questions.
Frequently asked
How do I calculate X percent of a number?
Divide the percentage by 100 and multiply by the number. For example, 25% of 200 is (25 ÷ 100) × 200 = 50. Pick the 'X% of Y' mode above and enter the two values — the result and the formula appear instantly.
How do I work out a percentage increase or decrease?
Subtract the starting value from the new value, divide by the starting value, then multiply by 100. A positive result means an increase, a negative one means a decrease. The '% change' mode does it for you and labels the direction.
Does my data go to a server?
No. The calculator runs entirely in your browser as plain arithmetic. Nothing you type is uploaded, stored, or shared.