Percentage Calculator
Compute a percentage, ratio between values, or percent change/difference.
Quick utilityGeneral editable assumptionsGlobal-readyInteractive chart
Last updated: 2026-05-31
This calculator uses generic assumptions. Use advanced mode to override them for a more accurate result.
Inputs
Formula transparency
Source: admin-curatedPercentage formulas
X% of Y = X/100 × Y; X is what % of Y = X/Y × 100; change = (Y−X)/X × 100
Four common percentage formulas covering value, ratio, change, and difference.
How to use it
- Pick the mode: percent of a value, ratio, change, or difference.
- Enter the two numbers.
Example
- 20% of 150 = 30. From 80 to 100 is a +25% change.
What the result means
Percent change is relative to the starting value; percent difference is relative to the average of both.
Common mistakes
- Confusing percent change with percentage-point change.
- Swapping the base value in a change calculation.
Limitations
- A change from zero is undefined.
Frequently asked
- Change vs difference?
- Change is directional (X is the base); difference uses the average of both values as the base.
- Why doesn't it work when X = 0?
- You can't divide by zero in % change.
- Does it save my values?
- No, calculation is fully local in your browser.
- How many decimal places?
- Up to 4 to reduce rounding error.
- Negative values supported?
- Yes in all modes — note that sign affects the result.
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Results are estimates and not professional advice. Verify important decisions with a qualified professional.