# Circle Calculator

> Provide a radius, diameter, circumference, or area to calculate every main circle measurement.

Page: https://askcalculators.com/calculator/circle-calculator/
Definition: https://askcalculators.com/calculator/circle-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/circle-calculator/schema.json
Version: 2.0.0
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/circle-calculator/?given=radius&radius=10

## Inputs
- given: Known measurement; type=select; required; default=radius; values=radius|diameter|circumference|area
- radius: Radius; type=number; required; default=10; min=0.000001; showWhen=given:radius
- diameterInput: Diameter; type=number; required; default=20; min=0.000001; showWhen=given:diameter
- circumferenceInput: Circumference; type=number; required; default=62.831853; min=0.000001; showWhen=given:circumference
- areaInput: Area; type=number; required; default=314.159265; min=0.000001; showWhen=given:area

## Outputs
- radiusResult: Radius; format=number; primary
- diameter: Diameter; format=number
- circumference: Circumference; format=number
- area: Area; format=number

## Formula
D=2R; C=2πR; A=πR²; solve the known measurement for R, then calculate the rest.

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