Use the formula: C = 2πr
Or use the formula: C = πd
C = circumference
r = radius
d = diameter
Measure the radius or diameter
Multiply 2 × π × radius, or π × diameter
Use π ≈ 3.14 if needed
The result is the circle’s circumference
Use the formula: C = 2πr
Or use the formula: C = πd
C = circumference
r = radius
d = diameter
Measure the radius or diameter
Multiply 2 × π × radius, or π × diameter
Use π ≈ 3.14 if needed
The result is the circle’s circumference