# Percentage Calculator

> Solve five common percentage problems without changing pages.

Page: https://askcalculators.com/calculator/percentage-calculator/
Definition: https://askcalculators.com/calculator/percentage-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/percentage-calculator/schema.json
Version: 1.0.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/calculator/percentage-calculator/?operation=percentOf&x=20&y=500

## Inputs
- operation: Calculation; type=select; required; default=percentOf; values=percentOf|whatPercent|increase|decrease|change
- x: X; type=number; required; default=20
- y: Y; type=number; required; default=500

## Outputs
- result: Result; format=number; primary
- summary: Calculation; format=text

## Formula
X% of Y = (X ÷ 100) × Y

The selected mode changes the formula.

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.