Short answer: To work out what underfloor heating costs to run, divide the heat the room needs in a year (kWh) by your heat source's efficiency, then multiply by your fuel price. At the Ofgem price cap for October to December 2026 (electricity 26.32p/kWh, gas 7.97p/kWh), 2,400kWh of heat a year costs about £213 from a 90% efficient gas boiler, about £211 from a heat pump with a SCOP of 3, and about £632 from electric underfloor heating. The heat source and its efficiency matter far more than the floor itself.
Underfloor heating does not create heat. It delivers heat made by a boiler, a heat pump or an electric cable. So the running cost of any underfloor heating system comes down to three numbers: how much heat the room needs, how efficiently that heat is made, and what you pay per kWh.
This guide shows you how to estimate each one for your home, with worked examples. For a simple cost per kWh comparison of water and electric systems, see water vs electric underfloor heating. For what it costs to buy and fit, see underfloor heating cost in the UK.
How do you work out underfloor heating running costs?
Annual running cost = heat needed (kWh) ÷ efficiency × price per kWh. Follow these steps.
- Find the heat needed. Use your current bills, a heat loss calculation, or the method in the next section.
- Find your efficiency. A gas boiler is below 1 (we use 0.9 as an example). Direct electric is 1. A heat pump is its SCOP, for example 3.
- Find your unit price. Check your bill. The Ofgem cap averages for 1 October to 31 December 2026, by direct debit, are 26.32p/kWh for electricity and 7.97p/kWh for gas.
- Divide and multiply. Heat ÷ efficiency gives the fuel you buy. Fuel × price gives the cost.
- Add standing charges if you are comparing whole bills. They are 54.83p a day for electricity and 29.68p a day for gas under the same cap, and you pay them whatever you use.
Ofgem states that VAT has been removed from electricity bills from 1 October 2026 to 31 March 2027, so the electricity figures exclude VAT. Gas still carries 5% VAT.
How much heat will my underfloor heating use?
The easiest starting point is your current gas use, because the heat your rooms need does not change when you swap radiators for underfloor heating. Multiply your annual gas kWh by your boiler efficiency to get the heat delivered.
Ofgem's typical domestic consumption value for a medium user, from 1 July 2026, is 9,500kWh of gas and 2,500kWh of electricity a year. That gas figure covers heating, hot water and cooking. At an example 90% boiler efficiency, 9,500kWh of gas delivers about 8,550kWh of heat.
For a single room or a new extension, a heat loss calculation is better. It gives the room's design heat loss in watts on a cold day. The room uses much less than that on average across the season, so annual figures come from heating degree days or design software rather than simple multiplication. A heating engineer or heat loss software can do this for you.
What does underfloor heating cost to run each year?
Here are three worked examples. The heat figures are example values to show the method, not predictions for your home. Prices are the October to December 2026 cap averages.
| Example | Heat a year | Cost a year |
|---|---|---|
| 4m² bathroom, electric mat | 240kWh | About £63 |
| 20m² extension, gas boiler | 2,400kWh | About £213 |
| 20m² extension, heat pump | 2,400kWh | About £211 |
| 20m² extension, electric | 2,400kWh | About £632 |
Bathroom working: a 4m² mat at 150W/m² draws 0.6kW. If it runs the equivalent of 2 hours a day at full power for 200 days, that is 0.6 × 2 × 200 = 240kWh, and 240 × 26.32p = £63.17.
Extension working: gas: 2,400 ÷ 0.9 = 2,667kWh of gas × 7.97p = £212.53. Heat pump at SCOP 3: 2,400 ÷ 3 = 800kWh × 26.32p = £210.56. Electric: 2,400 × 26.32p = £631.68.
The pattern is clear: electric underfloor heating is reasonable for a small bathroom used in short bursts, but costs about three times as much as gas or a heat pump for the same heat over a larger area.
How much does heat pump efficiency change the cost?
A lot. Every step up in seasonal efficiency (SCOP) cuts the electricity a heat pump needs for the same heat. Here is the same 6,000kWh of heat a year at different SCOPs, at 26.32p/kWh.
| SCOP | Electricity used | Cost a year |
|---|---|---|
| 2.5 | 2,400kWh | About £632 |
| 3.0 | 2,000kWh | About £526 |
| 3.5 | 1,714kWh | About £451 |
| 4.0 | 1,500kWh | About £395 |
The Energy Saving Trust notes that lower flow temperatures let a heat pump run more efficiently, and underfloor heating's large surface lets it heat rooms with low flow temperatures. That is where underfloor heating earns its keep on running costs: not by needing less heat, but by helping the heat pump make it more cheaply. Our guide to underfloor heating with a heat pump covers design flow temperatures and pipe centres.
Is underfloor heating cheaper to run than radiators?
It can be, when the heat source runs more efficiently at the lower water temperature underfloor heating needs. The room's heat loss is the same either way, so the saving depends on how much the lower flow temperature improves the boiler or heat pump.
Worked example: switching a medium home from gas to a heat pump. 8,550kWh of heat (from 9,500kWh of gas at 90%) costs 9,500 × 7.97p = £757 a year on gas. From a heat pump at SCOP 3 it needs 2,850kWh of electricity, which costs about £750. If you then disconnect gas, you also stop paying the gas standing charge of 29.68p a day, or about £108 a year. The Energy Saving Trust notes that a heat pump on a time-of-use tariff can cost less to run than a gas boiler. This example treats hot water and cooking the same as space heating, so it is a rough guide only.
See underfloor heating vs radiators for the full comparison.
Should I leave underfloor heating on all the time?
For a screed floor, it is usually best to run it steadily with a modest night setback rather than switching it fully off and on. A screed takes hours to warm from cold, so turning it off overnight often means it runs hard in the morning and still feels cool.
- Screed floors: steady temperature, small setback overnight and when out.
- Overlay boards: respond faster, so normal timed periods work better.
- Electric mats under tile: run on a timer for the times you use the room.
- Heat pumps: follow the heat pump maker's guidance. The Energy Saving Trust notes its standard controls advice is written for boilers.
The Energy Saving Trust's general advice is a setback of about 12 to 15°C overnight or when out for boiler systems, with comfort and health taking priority.
What makes underfloor heating expensive to run?
High running costs usually come from the building or the set-up, not the pipe in the floor. Check these before blaming the system.
| Cause | Effect |
|---|---|
| No insulation under heating | Heat lost downwards |
| Carpet over 2.5 tog | Higher flow temp needed |
| Flow temp set too high | Lower boiler or HP efficiency |
| Loops not balanced | Some rooms overheat |
| Thermostat set high | More heat used |
| Electric as main heating | About 3x cost per kWh |
Insulation is the big one. Without it, a heated screed warms the ground or the ceiling below. See insulation under underfloor heating.
How can I cut underfloor heating running costs?
The biggest savings come from running at the lowest water and room temperatures that keep you comfortable.
- Set room thermostats to the lowest comfortable temperature. The Energy Saving Trust says that is 18 to 21°C for most people, and that turning down from 22°C to 21°C could save about £120 a year in Great Britain.
- Lower the flow temperature on the blending valve or heat pump until rooms just reach temperature on a cold day.
- Balance the loops so each room gets the flow it needs. See balancing underfloor heating loops.
- Use a thermostat in every zone so unused rooms run cooler.
- Choose a tariff that suits your heat source, such as a heat pump time-of-use tariff.
- Keep floor coverings thin. Tile and stone transfer heat best.
- Keep electric underfloor heating to small rooms used for short periods.
Products for this job
- Heatmiser neoStat V3, £77 inc VAT, October 2026, programmable per zone
- Heatmiser neoStat-e, £83, for electric mats with a floor sensor
- Heatmiser neoHub G3, £162, for app control and schedules
- Auto-balancing stainless steel manifold
- UFH non-mixing pump set, £215, for heat pumps
- Insulation boards for under the heating
- Edge insulation roll, from £10
Related guides: How much does underfloor heating cost in the UK?, Underfloor heating with a heat pump and Underfloor heating thermostats explained.
Design an efficient floor with MaxHeatUFH ProLoop. Add your rooms and floor type, and get a free loop design and full kit list with prices, set out for low flow temperatures. Start your design
Frequently asked questions
How much does underfloor heating cost to run per day?
It depends on the heat used. As an example, 13kWh of heat in a day costs about £1.15 from a 90% gas boiler and about £3.42 from electric underfloor heating, at October to December 2026 cap prices. Standing charges are extra.
How much does electric underfloor heating cost per hour?
Multiply the mat's power in kW by your unit price. A 4m² mat at 150W/m² is 0.6kW, so about 15.8p per hour at full power at 26.32p/kWh. Once the floor is warm, the thermostat cycles it, so the real cost is lower.
Is underfloor heating expensive to run with a heat pump?
No. At a SCOP of 3, a heat pump makes heat for about 8.8p/kWh at 26.32p electricity, close to a 90% gas boiler. Underfloor heating helps by letting the heat pump run at a lower flow temperature.
Does underfloor heating use more energy than radiators?
No. The room needs the same amount of heat either way. Underfloor heating can use less fuel when its lower water temperature makes the boiler or heat pump more efficient.
Is it cheaper to leave underfloor heating on low?
For screed floors, a steady temperature with a small setback usually works better than switching off, because screed is slow to warm. Overlay boards and electric mats can be run on normal timed periods.
What temperature should underfloor heating be set at?
Set room thermostats to the lowest comfortable temperature, 18 to 21°C for most people according to the Energy Saving Trust. Set the water temperature as low as gives that room temperature on a cold day.
Do the electricity prices include VAT?
Ofgem states that VAT was removed from electricity bills from 1 October 2026 to 31 March 2027, so the 26.32p figure has no VAT on it. The gas figure includes 5% VAT.
Sources: Ofgem: energy price cap, 1 October to 31 December 2026, Ofgem: revised typical domestic consumption values, Energy Saving Trust: underfloor heating, Energy Saving Trust: thermostats and heating controls, Energy Saving Trust: air source heat pumps