Circle Calculator

I know

Choose the one value you already have.

Value

Positive number (e.g., 10, 25.4, 100).

Unit (optional)

Used only for labeling (area uses unit²).

Decimal places

Controls rounding in outputs.

Circle – Quick Cheat Sheet

Notes & best practices

Enter only one known value at a time for clean results.
Keep unit labels consistent (e.g., all in cm or all in inches).
Increasing decimal places yields more precise outputs, but very large areas can overflow your chosen unit scale—consider switching units.