Free Online Percentage Calculator
Seven of the everyday percentage questions live here in one place: X% of Y, X is what percent of Y, increase and decrease, adding or subtracting a percentage, and the difference between two numbers. Every mode shows the formula it used, handles a zero denominator gracefully, and can pass results along in the URL.
- 100% free
- Private & safe
- Runs in your browser
Why use Percentage Calculator?
Percentage Calculator gives you accurate results instantly, with the underlying formula shown so you can trust the numbers.
- Runs instantly in your browser — nothing to install, nothing uploaded.
- Completely free, with no account, no watermarks and no usage limits.
- Handles X% of Y = (X/100) × Y; X is what % of Y = (X/Y) × 100; Increase % = ((new − old)/old) × 100; Difference % = |a − b| / ((a + b)/2) × 100.
- Pick the mode that matches your question.
- Works on any device — desktop, tablet and phone — and is fully keyboard accessible.
What it can do — and its limits
- Finds a percentage of a number, what percentage one number is of another, and percentage increase or decrease.
- Updates live as you type.
- Calculated in your browser.
How to use Percentage Calculator
- Pick the mode that matches your question.
- Enter the numbers; the result and the formula used update instantly.
- Adjust decimal precision, copy the result, or share the URL with the values filled in.
- Division by zero is handled gracefully with a clear message.
Examples
- What is 15% of 240? → 36.
- 45 is what percent of 180? → 25%.
- A price rose from 80 to 100 → a 25% increase.
Worked example
Input
What is 15% of 240?
Output
36 (240 × 15 ÷ 100).
Formulas
- X% of Y = (X/100) × Y
- X is what % of Y = (X/Y) × 100
- Increase % = ((new − old)/old) × 100
- Difference % = |a − b| / ((a + b)/2) × 100
Limitations
- Percentage difference is undefined when both values are zero.
- Results are rounded to your chosen precision for display.
Common problems & fixes
Confusing percentage points with percent change.
Going from 10% to 12% is +2 percentage points but a +20% relative change — they're different.
Expecting an increase then decrease to cancel.
+50% then −50% doesn't return to the start (1.5 × 0.5 = 0.75).
Frequently asked questions
What is the difference between percentage change and difference?
Change compares a new value to an original baseline; difference compares two values relative to their average, with no baseline.
Can I share a calculation?
Yes. The values are placed in the URL so you can copy and share a link that reopens the same result.
What happens if I divide by zero?
The tool detects zero denominators and shows a clear message instead of an incorrect result.