Circumference of a Circle Calculator C = 2πr. Radius Circumference 43.982 Diameter 14 Step-by-step with your numbers: 1. Values used: 2. Radius = 7 3. Circumference = 43.982 4. Diameter = 14 Did we solve your problem today? 👍 Yes 👎 No Thanks for the feedback! Circumference = 2πr. FAQ From diameter? C = πd. Related calculators Circle Calculator Find a circle's area, circumference and diameter from its radius. Area of a Circle Calculator A = π r². Circumference Calculator Find a circle's circumference and diameter from the radius.