Underfloor Heating Calculator: Wattage & Running Cost
What This Calculator Does
This tool gives you a planning-level estimate of the installed electrical power and annual running cost of an electric underfloor heating system. It uses the real power densities published on SunAura’s product pages for heating film, heating mats, and heating cables, then applies your room area, daily runtime, and local electricity tariff.
All outputs are labelled estimate. The actual installed load depends on floor build-up, insulation level, room orientation, set-point temperature, and thermostat scheduling. For a confirmed figure, send us your floor plan and our engineers will size each zone and return a factory quote the same day.
Wattage & Running Cost Calculator
How to Read Your Result
The calculator outputs two numbers that matter for planning: installed power in kW (what your circuit breaker and thermostat must handle) and annual running cost in your local currency (what your utility bill will roughly show). Both are estimates — here is how to interpret them correctly.
What does 100–200 W/m² actually mean?
Power density per square metre is the fundamental sizing parameter. A well-insulated living room with laminate or engineered wood floor typically needs 100–150 W/m² as a supplementary heating source. A bathroom with tiled floor, poor underfloor insulation, and cold air movement may need 160–200 W/m² to reach a comfortable surface temperature of 24–28 °C. Above 200 W/m², the system is usually designed as primary heat source, which requires a well-insulated room envelope and a dedicated circuit.
Why the ±20% range?
The mid-point cost assumes typical thermostat programming (morning preheat, evening hold, night setback). If your room is poorly insulated, has single-glazed windows, or you run the system continuously at a high set-point, actual consumption can be 20–40% higher. Conversely, a well-insulated new-build with smart zoning and night setback can come in 15–25% below the estimate. The range band is there to reflect real-world variation honestly.
Insulation is the single biggest lever
A 5 mm insulation board under the heating element reduces downward heat loss by roughly 50% compared with installing directly on a concrete slab. For retrofits, adding insulation is usually the most cost-effective upgrade you can make — it both lowers running cost and allows a lower W/m² density to still deliver the same surface comfort.
Film vs. Mat vs. Cable — Quick Selection Guide
| Product | Typical W/m² | Best floor finish | Best application |
|---|---|---|---|
| Graphene heating film | ~150–200 W/m² (adjustable) | Laminate, engineered wood, vinyl, carpet | Dry renovation, fast heat-up, wall/ceiling options |
| Heating mat | 160 W/m² rated | Ceramic tile, stone, porcelain | Bathrooms, kitchens, wet areas — in tile adhesive |
| Heating cable | ~150–250 W/m² (effective) | Screed, concrete bed, tile adhesive | New-build screed, primary heating, snow-melt zones |
Real Specs Recap (from SunAura product pages)
| Parameter | Heating Film | Heating Mat | Heating Cable |
|---|---|---|---|
| Power output | ~100–220 W/m² (adjustable) | 160 W/m² rated | 10–30 W/m linear (15–25 W/m for floor) |
| Voltage | 110 V / 220–230 V | 110 V / 230 V | 110 V / 220–240 V |
| Water resistance | IP67 | Double-insulated, shielded | IPX8 |
| Thickness / profile | Thin flexible sheet | 3.6 mm (cable on mesh) | Round cable, selectable gauge |
| Electrothermal efficiency | > 99% | — | — |
| Warranty / design life | 15-year warranty | 25-year warranty | 15–25 year design life |
| Certifications | CE, RoHS, ISO 9001 | CE, RoHS, ISO 9001 | CE, RoHS, ISO 9001 |
| Installation format | Dry lay under finish floor | In tile adhesive | In screed, tile adhesive, or clips |
Specs above are summarised from the live SunAura product pages linked in the table above. For full datasheets and test reports, request documentation.
Frequently Asked Questions
How accurate is this calculator estimate?
The calculator uses real power densities from SunAura product pages and standard electrical formulas (kW = area × W/m² ÷ 1000; annual cost = kW × daily hours × season days × electricity price). The ±20% range band accounts for typical insulation and thermostat programming variation. For a confirmed number for your specific project, send us your floor plan with room dimensions and floor finish — our engineers size each zone and return a factory quote the same day.
What factors affect the running cost the most?
Three variables dominate: (1) insulation — underfloor insulation board cuts downward loss by roughly half; (2) thermostat programming — night setback and smart zoning can reduce consumption by 20–35% compared with continuous heating; (3) electricity tariff — off-peak rates, economy 7-style tariffs, and solar self-consumption can dramatically lower the effective cost per kWh. The calculator lets you adjust all of these inputs.
How many watts per square metre do I actually need?
As a planning rule of thumb: 100–150 W/m² for well-insulated living spaces with laminate/wood finishes; 160 W/m² for tiled bathrooms and kitchens (the SunAura mat standard); 180–250 W/m² for cold rooms, primary heating, or poorly insulated retrofits. Your exact requirement depends on floor build-up, set-point temperature, and local climate — our engineers confirm this with a free layout drawing.
Can I install underfloor heating myself (DIY)?
Unrolling and positioning heating film or mat is straightforward for a competent DIYer. However, the electrical connections — copper busbar terminations, cold tail wiring, and thermostat connection to the mains — must be done by a qualified electrician in compliance with local wiring regulations. Every zone should be continuity-tested before the floor finish is laid. For cable installations in screed, professional installers are strongly recommended.
Is this factory-direct pricing?
SunAura manufactures heating film, mats, and cables in our own Qingdao facility and sells factory-direct — no trading-company markup. The calculator estimates running cost (electricity bill), not equipment price. Equipment pricing depends on film width, power density, mat area, cable length, order volume, and export terms (EXW/FOB). Send us your room list and we return a written quote with a free layout drawing the same day.
What size circuit breaker do I need?
The calculator’s installed kW figure gives you the total load: divide by your supply voltage (e.g. 230 V) to get the current in amps, then size the circuit with appropriate headroom and an RCD/RCCD for wet areas. As a rough guide: a 2 kW system on 230 V draws about 8.7 A and typically uses a 10–16 A dedicated circuit. Always have a qualified electrician confirm the final circuit design and protective device sizing.
Get a Confirmed Factory Quote
This calculator gives you a planning estimate. For an exact, project-specific sizing with zone drawings, circuit schedules, and written factory-direct pricing:
Request a free layout & quote →
Meanwhile, explore the full product range: