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Pipe Thermal Expansion Loop Sizing Calculator

Calculate the required leg length of a pipe expansion loop to safely absorb thermal expansion movement.

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 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Required loop leg length

2.06 ft

Check your inputs

This simplified formula is a commonly-used approximation for preliminary sizing — final expansion loop design should be verified against the pipe manufacturer's or ASME B31 piping code stress analysis for critical or high-temperature systems.

For the dimensions entered, expect a required loop leg length of 2.06 ft. Moderate confidence — sound arithmetic, but allow for the variation any real site introduces. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

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

  • Simplified expansion loop sizing: L(ft) ≈ 0.73 × √(Do(in) × ΔL(in)), a commonly-cited approximation for sizing a square/U-shaped expansion loop's leg length from the pipe's outside diameter and expected linear expansion, keeping bending stress within allowable limits

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Frequently asked questions

What does this loop leg length formula estimate?
It's a commonly-cited approximation, L(ft) ≈ 0.73 × √(outside diameter in × expected linear expansion in), for sizing the leg length of a square or U-shaped pipe expansion loop so that bending stress from the absorbed thermal movement stays within allowable limits.
Is this formula sufficient for final expansion loop design?
No — treat it as a preliminary sizing approximation only. Final expansion loop design should be verified against the pipe manufacturer's data or an ASME B31 piping code stress analysis, especially for critical or high-temperature systems.
What inputs does the formula need?
Just the pipe's outside diameter and the expected total linear expansion of the anchored run — both in inches. The expected expansion itself should come from the pipe material's coefficient of thermal expansion, the run length, and the expected temperature swing.