Radiant Floor Heating Calculator
Your room
Fixed fixtures (vanity, tub, cabinets) get no heat.
Heated mat needed
45 sq ft
- Room area
- 60 sq ft
- System wattage
- ~540 W
- Daily energy
- 2.2 kWh
- Est. monthly cost
- $11.02
Buy the mat size at or just under your heated area — mats cannot be cut, only the mesh can.
Tools the pros use for this job
Heating Mat
Pre-spaced mats install 3× faster than loose cable.
Uncoupling Membrane
Membranes with cable channels hold heat wire and protect tile.
Thinset Mortar
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How this calculator works
Heated area = room area minus anything fixed to the floor (vanity, tub, toilet footprint, cabinets, appliances). A typical bathroom loses ~25%, a kitchen with cabinets ~40%. Heat under a cabinet can damage it and wastes energy.
Floor-warming systems run ~12 watts per square foot; systems meant as a primary heat source run ~15. Running cost assumes the mat cycles at full power for your daily hours — thermostats with floor sensors typically cut real consumption 20–30% below that.
Frequently asked questions
Is radiant floor heat expensive to run?
Less than people fear: a 45 sq ft bathroom mat at 12 W/sq ft draws about 540 W — like a few light bulbs. At 4 hours a day and $0.17/kWh that is roughly $8–11 per month.
Can radiant heat crack my tile?
Not if installed correctly. Embed the cable fully in thinset or self-leveler, never turn the heat on until the mortar has cured (usually 7–28 days per manufacturer), and ramp the temperature gradually.
Mat or loose cable?
Mats are faster and give perfectly even spacing — best for rectangular rooms. Loose cable costs less per square foot and fits irregular shapes better. Both end up the same temperature under tile.
Related calculators
- Thinset & Mortar CalculatorBags of thinset by trowel notch size and coverage.
- Backer Board CalculatorCement board sheets, screws, and tape for floors and walls.
- Self-Leveling Compound CalculatorBags of leveler by area and depth of the low spots.
- Tile Cost EstimatorTotal project cost: tile, grout, mortar, trim, and labor.
Guides worth reading next
- Heated Tile Floors: How Radiant Heat Under Tile Actually WorksMat vs cable systems, the square footage you actually heat (not the whole room), wiring and thermostat basics, running costs, and thinset rules over mats.
- Are Heated Tile Floors Worth It? The Math and the ComfortInstalled cost per square foot, monthly running costs, resale value, and the honest comfort case for radiant heat under bathroom tile.
- How to Measure a Room for Tile (Step by Step)Measure any room for floor or wall tile: handle closets and alcoves, convert inches to decimals, subtract fixtures, and add the right waste percentage.