Circumference Calculator (Radius)
Calculate circle circumference instantly using the radius. Features high-precision Pi and variable decimal output for engineering accuracy.
Circumference (C):
About
This tool determines the total boundary length of a circle based on its radius. Speed and precision are the priorities here. Unlike standard calculators, this tool utilizes a high-precision storage of Pi (π) to prevent rounding errors in large-scale engineering projects, such as tank construction or track layout. Users can adjust the decimal precision of the output to suit their reporting standards, from rough estimates to microscopic tolerances.
circumference
circle calculator
radius to circumference
pi calculator
geometry tool
Formulas
The circumference is linearly proportional to the radius.
C = 2 × π × r
Reference Data
| Parameter | Value/Formula | Notes |
|---|---|---|
| Formula | C = 2πr | Standard Euclidean geometry |
| Pi (π) | 3.1415926535... | Irrational constant |
| Radius (r) | d / 2 | Distance from center to edge |
| Area Relation | A = Cr / 2 | Alternative area derivation |
Frequently Asked Questions
We use JavaScript's Math.PI, which provides approximately 15 digits of precision (3.141592653589793), sufficient for almost any physical calculation.
You must first solve for the radius: r = square root of (Area / Pi), then use that radius here.
No. If you input meters, the output is meters. If you input pixels, the output is pixels.