How is it calculated?
A = π r² · C = 2 π r · d = 2 r
π (pi) is about 3.14159. The calculator uses full precision.
Circle calculator
Know one measurement of a circle? Enter it to get the radius, diameter, circumference and area.
Last updated: · By Furkan Çetinkaya · About & Methodology
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Circle values for radius 1 to 10
Diameter d = 2r, circumference C = 2πr, area A = πr² (π ≈ 3.14159).
| r | d | C = 2πr | A = πr² |
|---|---|---|---|
| 1 | 2 | 6.28 | 3.14 |
| 2 | 4 | 12.57 | 12.57 |
| 3 | 6 | 18.85 | 28.27 |
| 4 | 8 | 25.13 | 50.27 |
| 5 | 10 | 31.42 | 78.54 |
| 6 | 12 | 37.70 | 113.10 |
| 7 | 14 | 43.98 | 153.94 |
| 8 | 16 | 50.27 | 201.06 |
| 9 | 18 | 56.55 | 254.47 |
| 10 | 20 | 62.83 | 314.16 |
Common questions
How do I find the radius from the circumference?
Divide the circumference by 2π (about 6.283).
How big is a 30 cm pizza?
Diameter 30 cm means radius 15 cm and an area of about 707 cm².