Percentage Calculator
Calculate percentages instantly — find X% of Y, what percentage X is of Y, and percentage change between two values.
Results are for general guidance only — not professional advice. Learn more.
How to use this tool
Select a calculation mode and enter your numbers — results update instantly as you type. This tool covers the four most common percentage calculations:
- % of a Number: Find what a given percentage of a number is. For example, 15% of 200 = 30.
- What % is X of Y?: Determine what percentage one value is of another. For example, 30 is 15% of 200.
- % Change: Calculate the percentage increase or decrease between an original value and a new value.
- Increase / Decrease: Apply a percentage to increase or decrease a number and see both results at once.
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Frequently asked questions
How do I calculate a percentage of a number?
To find X% of a number Y, multiply Y by X and divide by 100. For example, 15% of 200 = (200 × 15) / 100 = 30.
How do I calculate what percentage one number is of another?
To find what percentage A is of B, divide A by B and multiply by 100. For example, 30 is what percentage of 200? (30 / 200) × 100 = 15%.
How do I calculate percentage change?
Percentage change = ((New Value - Old Value) / Old Value) × 100. A positive result is a percentage increase; a negative result is a percentage decrease. For example, going from 80 to 100 is a 25% increase.
How do I increase or decrease a number by a percentage?
To increase a number by X%, multiply it by (1 + X/100). To decrease it by X%, multiply it by (1 - X/100). For example, 200 increased by 15% = 200 × 1.15 = 230.