For a circle, use the circumference formula: C = πd
Solve for diameter: d = C ÷ π
If you want the width of the circle, use the diameter as the width
So, width = C ÷ π
If you need the radius instead, use r = C ÷ (2π)
For a rectangle or other shape, circumference may not apply directly
Make sure the shape is a circle before using this formula