Circle Calculator
Calculate circle area, circumference, and diameter.
- 100% free
- Private in browser
- No signup
- No watermarks
Result
- Diameter
- 10
- Circumference
- 31.4159
- Area
- 78.5398
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About Circle Calculator
Circle Calculator on TheToolss computes a circle’s diameter, circumference, and area from its radius using the standard formulas (d = 2r, C = 2πr, A = πr²). Enter the radius in any unit and read all three results at once. It is handy for geometry homework, design, and DIY projects. The result updates as you type. It runs in your browser — free, private, and no signup.
How to use Circle Calculator
- Enter the radius.
- Read the diameter, circumference, and area.
- Change the radius to recompute.
Key features
- Area, circumference, and diameter
- Uses precise π
- Works in any unit
- Instant results
- Private in-browser calculation
Frequently asked questions
- Is the Circle Calculator free?
- Yes. It is free on TheToolss with no signup.
- What formulas are used?
- Diameter = 2r, circumference = 2πr, and area = πr², where r is the radius.
- Can I enter the diameter instead?
- Enter half the diameter as the radius. The tool takes radius as its input.
- What units does it use?
- Any unit — the outputs are in the same unit as your radius (area in square units).
- Is my data uploaded?
- No. The calculation runs in your browser.
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