Percentage Calculator
Find a percent of a number, what percent one number is of another, percent change, and a value after a percent increase or decrease, with the formula shown.
What is Y% of X?
X is what percent of Y?
Percent change from X to Y
X increased or decreased by Y%
How to use
- Pick the card that matches your question, such as “What is Y% of X?” or “Percent change from X to Y”.
- Type the two values. The result appears instantly with the formula below it, so you can check or reuse it.
- Set “Decimal places” for the results, click “Copy” on a card to grab its result, or click “Example” to fill in all four cards.
FAQ
How do I calculate Y% of X?
Multiply and divide by 100: 15% of 200 = 200 × 15 ÷ 100 = 30. Useful for tips, service charges, commissions and tax.
How is percent change calculated?
(new − original) ÷ original × 100%. Going from 80 to 100 is (100 − 80) ÷ 80 = +25%, while going from 100 to 80 is (80 − 100) ÷ 100 = −20%: the same difference of 20, measured against a different starting point.
Why doesn’t +10% then −10% get back to the start?
The second 10% is taken from the higher price: 100 × 1.1 × 0.9 = 99, 1% below where you started. After a 10% rise, a drop of about 9.09% brings it back.
What is the difference between percent and percentage points?
A rate moving from 2% to 3% rises by 1 percentage point, but by 50% in relative terms ((3 − 2) ÷ 2). Financial news usually keeps the two apart.
Are the results exact?
Yes. Calculations use exact fractions, so there are no floating-point errors like 0.1 + 0.2 = 0.30000000000000004. Results are rounded only for display, and the formula shows “≈” when rounding happened.
Is my data uploaded?
No. Everything is calculated in your browser, with no network connection needed.
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