Percentage Calculator
Calculate a percentage of a number, what percent one number is of another, or percent change.
- Runs locally in your browser
- No upload required
Try it
Supported formats
Privacy
Runs entirely in your browser. Your input is never uploaded, stored, or sent to a third party.
15% of 200 is 30.
How it works
- Read the two operands for the selected mode.
- Applied the mode's formula.
- Rounded the result to 12 significant digits.
(200 * 15) / 100 = 30- Percentage points and percent are different units; this tool computes percent.
Methodology
- Read the two operands as numbers and apply the percentage identity: amount = whole × (percent ÷ 100).
- For what-percent, divide the part by the whole and multiply by 100; for percent-change, compare the new value against the original as a relative change.
- Reject a zero base for the ratio modes, because the result is undefined.
Usage
- Choose the calculation mode.
- Enter the two operands.
- Read the result and the formula used.
Examples
These are examples, not current values: they use fixed inputs, while the interactive tool computes live results in your browser.
Percent of
{
"mode": "percent-of",
"a": 200,
"b": 15
}What percent
{
"mode": "what-percent",
"a": 30,
"b": 200
}Percent change
{
"mode": "percent-change",
"a": 200,
"b": 250
}Limitations
Choosing the right mode
Use percent-of when you know a rate and want an amount. Use what-percent when you know two amounts and want a rate. Use percent-change when you know a start and an end and want the relative movement.
Frequently asked questions
- What is the difference between percent and percentage points?
- Moving from 10% to 15% is a 5 percentage-point increase but a 50% relative increase. This tool reports the relative percent change.
Sources
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