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Circumference Calculator

Find the circumference and radius of a circle from its diameter, for round posts, pipes, or tanks.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-25 · v1.0.0

Market
Imperial · sales tax
3.28 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Circumference

10.31 ft

High confidence
Radius
1.64 ft

With the figures above, the circumference comes to 10.3 ft. Behind that figure, radius is the biggest single quantity at 1.64 ft; start there if the total looks wrong. Note that diameter sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. This is calculated for United States and cites IRC 2024. Building in another market? Change the selector above so the units and code reference follow.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Circumference = diameter x pi; radius = diameter / 2

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

What's this useful for on a construction project?
Common uses include finding how much wrap material (tree protection wrap, pipe insulation, cable ties) fits around a round post, column, or pipe, or estimating a round planter or tank's outer wrap length.
How is this different from area?
Circumference is the distance around the outside edge of a circle (useful for wrapping or fencing something round); area is the flat surface enclosed within it — they're related but answer different questions.
Does this work for ovals or irregular round shapes?
No — this assumes a true circle. Ovals and irregular curved shapes need a different formula or a direct measurement with a flexible tape.