Percentage Calculator
The three percentage questions people actually ask — answered as you type, privately in your browser.
What is X% of Y?
X is what percent of Y?
Percent change from X to Y
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The three percentage questions
Almost every percentage problem in daily life is one of three things, and this page has a calculator for each:
- Percent of a value — "What is 15% of 80?" Answer: 80 × 15 ÷ 100 = 12. Discounts, tips, tax rates and commission all live here.
- What percent is X of Y? — "12 out of 80 is what percent?" Answer: 12 ÷ 80 × 100 = 15%. Test scores, completion rates and share-of-total questions.
- Percent change — "from 50 to 65?" Answer: (65 − 50) ÷ 50 × 100 = +30%. Price changes, salary raises, growth metrics.
Where these show up
Shopping: a "30% off" tag on a 89.90 jacket is 26.97 off — you'd pay 62.93. Stack a second discount and remember: percentages don't add. Two 20% discounts are not 40% off but 36% (the second 20% applies to the already-reduced price).
Money: a raise from 3,200 to 3,400 per month is a 6.25% increase — compare that to inflation to know if it's real. A portfolio that drops 20% needs a 25% gain just to break even, which is why losses hurt more than the same gain feels good.
School and work: 47 out of 52 correct is 90.4%. A metric improving from 2.4% to 3.0% is up 0.6 percentage points — but a 25% relative improvement. Percentage points and percent change are different things; headlines mix them up constantly.
Quick mental shortcuts
10% of anything is the decimal moved one place (10% of 340 = 34). 5% is half of that; 1% is two places left. For 15%, add 10% + 5% (15% of 340 = 34 + 17 = 51). For 25%, halve twice. These cover most real-life cases; for the rest, the calculator is right here — and it never rounds until the final display.
Frequently asked questions
How do I calculate X% of Y?
Multiply Y by X and divide by 100: 15% of 80 is 80 × 15 ÷ 100 = 12. The first calculator on this page does it instantly.
How do I find what percent X is of Y?
Divide X by Y and multiply by 100: 12 out of 80 is 12 ÷ 80 × 100 = 15%. Use the second calculator on this page.
How is percentage change calculated?
Change = (new − old) ÷ old × 100. Going from 50 to 65 is (65 − 50) ÷ 50 × 100 = +30% (an increase). A negative result is a decrease.
What's the difference between percentage points and percent?
A rate going from 10% to 12% rose by 2 percentage points — but that's a 20% relative increase. News headlines often confuse the two; this page computes the relative percent change.
Is my data private?
Yes. All calculations run in your browser. Nothing is uploaded, logged or stored.