Percentage Calculator
Calculate percentages, increases, decreases and percentage differences.
How to Use
- Choose which calculation you need from the options above the form.
- Enter the numbers the calculation asks for — no need to type a % sign.
- The result updates instantly as you type.
- Use Copy Result to copy the answer to your clipboard.
Formula
- X% of Y
- result = Y × (X ÷ 100)
- X is what % of Y
- result = (X ÷ Y) × 100
- Percentage change
- result = ((new − original) ÷ |original|) × 100
- Increase by X%
- result = value × (1 + X ÷ 100)
- Decrease by X%
- result = value × (1 − X ÷ 100)
Worked Example
What is 15% of 200?
- Convert 15% to a decimal: 15 ÷ 100 = 0.15
- Multiply by the value: 200 × 0.15 = 30
Result: 30
About This Tool
What this tool does
This calculator performs the five most common percentage operations: finding a percentage of a number, finding what percentage one number is of another, finding the percentage change between two values, and increasing or decreasing a value by a percentage.
When to use it
Use it for everyday percentage math — tips, discounts, markups, grade calculations, or working out how much something has grown or shrunk compared to a previous value.
What the result means
The result is always the same unit-less percentage figure or the resulting value, matching the operation you selected. A percentage change result is positive for an increase and negative for a decrease.
Assumptions & limitations
Percentage change uses the magnitude (absolute value) of the original value as the base, which keeps the sign of the result meaningful even when the original value is itself negative. The calculator does not round intermediate steps — only the final displayed result is rounded.