Use the formula: C = 2πr
Or use the formula: C = πd
C = circumference
r = radius
d = diameter
Multiply 2 by π and by the radius to get the circumference
Multiply π by the diameter to get the circumference
Use the formula: C = 2πr
Or use the formula: C = πd
C = circumference
r = radius
d = diameter
Multiply 2 by π and by the radius to get the circumference
Multiply π by the diameter to get the circumference