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Radiant Floor Heating Cable Spacing Calculator

Calculate the total loose radiant heating cable length needed for a floor at a given loop 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 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Total cable length needed

328.08 ft

Check your inputs

Confirm your specific cable product's minimum bend radius and total length/wattage rating against your circuit before finalizing spacing — spacing that is too tight risks exceeding the cable's rated length for a single loop.

Running these inputs gives 100 m as the total cable length needed. Expect some drift against the real job; the calculation is solid but conditions on site are not. Currently reading for United States under IRC 2024 — pick a different market above and the figures re-cast accordingly.

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

  • For loose cable (not a pre-made mat) laid in a serpentine pattern, total cable length ≈ floor area ÷ spacing between adjacent cable runs

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

Why does tighter spacing use more cable?
The cable snakes back and forth across the floor in a serpentine pattern — the closer together the runs are spaced, the more total passes (and therefore total length) are needed to cover the same floor area.
What happens if the calculated length exceeds my cable's rated maximum loop length?
Every loose radiant cable product has a maximum length per circuit set by its resistance and rated wattage — if your calculated length exceeds that, you will need to widen the spacing, split the floor into multiple circuits, or choose a different cable product rather than exceeding the manufacturer's rating.
Does this apply to pre-made heating mats?
No — pre-made mats already have the cable fixed to a mesh backing at a set spacing and are sized by area, not by this loose-cable length calculation. Use this calculator only for loose cable installed by hand.