16 / percentage-calculator
free online tool
Percentage Calculator
Calculate percentages, percentage changes, and more in seconds.
how to use
- 01
Choose the calculation type (e.g. 'What is X% of Y?').
- 02
Enter the required numbers.
- 03
The result is calculated instantly.
about
What is this tool?
Percentage Calculator covers the most common percentage calculations: finding a percentage of a value, calculating what percentage one number is of another, and computing percentage increase or decrease. All calculations are instant and run locally in your browser.
why use this tool
- -No mental math — get accurate results instantly.
- -Covers all common percentage scenarios.
- -Useful for finance, discounts, grades, and statistics.
- -Works offline — no server required.
features
- -What is X% of Y?
- -X is what % of Y?
- -Percentage increase / decrease calculator.
- -Instant results with clear formula display.
comparison
Percentage Calculation Types
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | (X / 100) × Y | What is 20% of 80? → 16 |
| X is what % of Y? | (X / Y) × 100 | 16 is what % of 80? → 20% |
| % increase from A to B | ((B - A) / A) × 100 | 50 → 75: +50% increase |
| % decrease from A to B | ((A - B) / A) × 100 | 100 → 75: −25% decrease |
All processing happens entirely in your browser using JavaScript. No files, text, or data are ever sent to a server. Your data stays on your device.
✦ tip from dragontail
When reviewing Dragontail's app download metrics, I use percentage change almost daily. A jump from 200 to 350 downloads sounds impressive, but it's a 75% increase — much more meaningful as a number. Conversely, a drop from 1,000 to 980 is only −2%, which is statistical noise. Always convert absolute changes to percentages before drawing conclusions from your data.
faq
How do I calculate a discount?
Use 'What is X% of Y?' — enter the discount percentage and the original price to find the discount amount.
How is percentage change calculated?
Percentage change = ((New - Old) / Old) × 100. A positive result is an increase; negative is a decrease.
Is rounding applied?
Results are shown to two decimal places. You can round further as needed.