Percentage Calculator
Calculate X% of a number, the share of a value in a total, the percentage change between two values or the effect of an increase or decrease.
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How does it work?
The calculator covers the four most common percentage calculations:
- X% of Y: Y × X ÷ 100.
- Share in %: value ÷ total × 100.
- Percentage change: (final − starting) ÷ |starting| × 100.
- Increase or decrease: value × (1 + change ÷ 100).
The result updates as you type. The calculation runs in your browser: no data is sent.
Examples
A 30% discount on a $79 item
“X% of Y” mode: 30% of 79 = $23.70 off. To get the discounted price directly, use the “Increase or decrease” mode with −30%: 79 × 0.70 = $55.30.
A rent going from $850 to $884
“Percentage change” mode: (884 − 850) ÷ 850 × 100 = +4%. The rent increased by 4% between the two dates.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage, then divide by 100. For example, 15% of 240 = 240 × 15 ÷ 100 = 36.
How do I calculate the percentage change between two values?
Subtract the starting value from the final value, divide by the starting value, then multiply by 100. A negative result means a decrease.
Does a 10% increase followed by a 10% decrease bring you back to the start?
No. 100 increased by 10% gives 110, and 110 decreased by 10% gives 99. The decrease applies to a higher base than the increase.
Can I enter decimal numbers?
Yes, with a decimal point: “12.5” is accepted, and thousands separators (“1,250”) are ignored. Results are rounded to two decimal places for display.