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Radiant Floor PEX Tubing Calculator

Estimate the length of PEX tubing needed for a radiant floor heating loop, based on area and tube spacing.

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

PEX tubing needed

315.74 linear ft of PEX

Check your inputs

This estimates tubing length only. Actual loop layout, maximum loop length per manifold circuit, and manifold port count should be confirmed against your specific radiant system's design guidelines.

Tubing before manifold allowance
287.04 linear ft

For the dimensions entered, expect a pex tubing needed of 316 linear ft of PEX. Note that floor area sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. 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

  • Standard radiant-floor industry formula: tubing length (ft) = floor area (sq ft) x (12 / tube spacing in inches)
  • 10% extra is standard to account for manifold connections, wall penetrations, and the return run at each loop's start and end

Your workspace

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Frequently asked questions

Does tighter tube spacing always mean better heating?
It means more heat output per square foot for a given water temperature, which helps in high heat-loss areas — but it also costs more tubing and increases pump head. Most manufacturers publish spacing recommendations by zone type.
Is there a maximum loop length I should worry about?
Yes — most PEX radiant systems have a maximum recommended loop length (often around 300 ft, tubing-diameter dependent) before pressure drop gets too high for the circulator pump. Large areas need multiple loops from a manifold, not one continuous run.
Does this account for the tubing needed to reach the manifold?
Only loosely, via the 10% allowance — for manifolds far from the heated area, add that supply/return run length separately.