Circumference to Diameter Calculator
Convert a known circumference back to diameter using the formula d = C / pi. This reverse calculation is useful when you can measure around a circular object (like wrapping a tape measure around a tree, pipe, or column) but need to know how wide it is across the center.
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Formula
How it works: Divide the circumference (the total distance around the circle) by pi (approximately 3.14159) to get the diameter, which is the straight-line distance across the circle through its center.
Worked Example
Frequently Asked Questions
When would I need to convert circumference to diameter?
This is common when you can wrap a tape measure around an object (tree trunk, pipe, column, barrel) but cannot measure across it directly. Dividing the circumference by pi gives the diameter.
Can I use decimal circumference values?
Yes. The calculator supports any positive decimal value, which is important for precise engineering and scientific measurements.
What if the circumference is zero?
A circumference of zero means the circle has no size, resulting in a diameter of zero. In practice, ensure you enter a positive measurement.
How do I find the radius from circumference?
First divide the circumference by pi to get the diameter, then divide the diameter by 2 to get the radius. The formula is r = C / (2 x pi).
Can I use this Circumference to Diameter Calculator on my own web page?
You can. Look for the "Embed" button near the top of this calculator. It lets you pick a size, border style, and color palette, then gives you an iframe tag to paste into any webpage. The widget is responsive, loads fast, and costs nothing. More details at calculory.com/services/embed-calculators.
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