SettingsSettings for this calculationUS
The total floor area to be heated.
Measure the usable floor area the cable will cover, excluding anything fixed on top of it. This is a single circuit's zone rather than the whole building: cable is supplied in fixed lengths and each loop has a rated maximum, so a large slab is laid as several zones and each one is entered here separately.
The centre-to-centre spacing between adjacent runs of the cable loop.
Tighter spacing delivers more heat per square metre and uses more cable. Two quite different applications sit on this one sum: electric floor warming under a finish runs at 75-150 mm (3-6 in), while cable laid in a slab to hold a temperature or stop frost heave under a cold store runs at 300 mm and wider. Take the figure from the design, not from the default.
Total cable length needed
330 ft
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.
They open the calculator with your figures already in it
Radiant Floor Heating Cable Spacing Calculator: 330 ft — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Show calculation logicHide calculation logic
How this was calculated
Formula source(s)
- For loose cable (not a pre-made mat) laid in a serpentine pattern, total cable length ≈ floor area ÷ spacing between adjacent cable runs
Inputs used
- Floor Area
- 110 sq ft
- Cable Loop Spacing
- 4 in
Confidence note: 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.
What this calculation does not cover
- Spacing is a heat output decision and this sum treats it as geometry. The cable has a fixed rating per unit length, so the spacing chosen sets the floor's output per unit of area - halve the spacing and you double it - and the figure that should drive it is the room's heat loss, or the holding load of the slab in a cold store. Pick a spacing to make a cable length come out neatly and you have quietly changed the floor's output, which shows up later as a room that never reaches temperature or a slab costing far more to run than it needed to.
- Nothing here caps the floor surface temperature. Finishes set their own limits - engineered wood and vinyl are commonly held to around 27 degrees C at the surface, and comfort guidance for occupied floors sits close to that, with a higher figure allowed in bathrooms and at perimeter strips - and that limit binds whatever spacing the arithmetic will accept. A tight spacing under a timber floor cooks the adhesive and opens the boards long before it heats the room properly, so the output is pulled back to suit the finish, not the cable.
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.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- For loose cable (not a pre-made mat) laid in a serpentine pattern, total cable length ≈ floor area ÷ spacing between adjacent cable runs
Cite this page
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.