Free Circle Calculator
Area, circumference, and diameter from a circle radius.
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Inputs
Result
Circumference
31.4159
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Short answer
Area, circumference, and diameter from a circle radius.
What is the Circle Calculator?
Area, circumference, and diameter from a circle radius.
How does the Circle Calculator work?
Enter the inputs above and read the result.
Formula
Variables
Explanation
π ≈ 3.14159265.
Examples
Applications
Advantages
Limitations
Common mistakes
Tips
Related concepts
The Circle Calculator sits inside the Math Calculators hub, in the geometry & shapes cluster. Length, area, volume and angle in two and three dimensions. Understanding the terms below makes the output easier to interpret and easier to compare against neighbouring measures.
Practical use cases and industry applications
Understanding Circle
Area, circumference, and diameter from a circle radius. Within math calculators, circle belongs to the geometry & shapes cluster, where it shares terminology and assumptions with closely related tools.
Learning how circle is calculated
π ≈ 3.14159265. Working through the variables one at a time — — makes the result reproducible by hand and easier to sanity-check.
Using circle to make a decision
Because outputs depend on the assumptions you enter, run more than one scenario before committing to a figure.
How circle compares with related measures
area, perimeter, volume, surface area all describe adjacent aspects of geometry & shapes. Comparing this calculator's output against those measures — using the related tools listed on this page — prevents a single metric from being read in isolation.
Frequently asked questions
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