How Much Does It Cost to Run a Immersion heater in the UK?
Last updated 5 October 2026 · Prices based on the Ofgem price cap (October 2026 – December 2026)
An immersion heater is a 3kW electric element inside a hot water cylinder. Heating a full tank from cold can take two hours or more, so it's an expensive way to heat water at standard rates — but cheaper on an off-peak tariff.
Appliance running cost calculator
A 3,000W immersion heater running 2 hours a day costs about £1.58 per day (£575 a year) at 26.32p/kWh.
- Per hour
- £0.79
- Per day
- £1.58
- Per week
- £11
- Per month
- £48
- Per year
- £575
- kWh per year
- 2,184
Based on 3000W ÷ 1,000 × 2h × 26.32p/kWh. Standing charge not included.
- Electric heater£958
- Immersion heater£575
- Oil-filled radiator£503
- Fan heater£383
- Electric shower£155
- Dehumidifier£153
- Tumble dryer£137
- Fridge freezer£114
- Electric oven£99
- Dishwasher£92
- Heated airer£74
- Kettle£57
- Washing machine£55
- Air fryer£51
- Slow cooker£44
- Electric blanket£10
Immersion heater running cost by wattage and time (at 26.32p/kWh)
| Wattage | 30 min | 1 hr | 2 hrs | 3 hrs |
|---|---|---|---|---|
| 3,000W | £0.39 | £0.79 | £1.58 | £2.37 |
Typical immersion heater cost per day, month and year
| Period | Energy used | Cost |
|---|---|---|
| Per hour | 3.00 kWh | £0.79 |
| Per day | 6.00 kWh | £1.58 |
| Per month | 182.0 kWh | £48 |
| Per year | 2184 kWh | £575 |
What affects the cost
Run time
How long until the thermostat reaches temperature.
Cylinder insulation
Poor lagging loses heat quickly.
Thermostat setting
Higher temperatures cost more.
Tariff
Off-peak rates can be less than half the price cap rate.
Cheaper alternatives to a immersion heater
• Gas boiler hot water • Economy 7 overnight heating • Solar diverter to use spare solar • Heat pump cylinder
How to reduce the cost
- Fit a timer and heat only when needed
- Check the cylinder jacket — at least 75mm
- Set the thermostat to 60°C
- Use Economy 7 overnight if available
Frequently asked questions
How much does a immersion heater cost per hour in the UK?
About £0.79 per hour for a 3,000W model at 26.32p/kWh.
How do I work out what my immersion heater costs to run?
Divide the wattage by 1,000 to get kW, multiply by the hours used, then multiply by your unit rate in pence. Our calculator above does this for you.
How much does an immersion heater cost per hour?
A 3kW immersion costs about £0.79 per hour at 26.32p/kWh.
Should I leave the immersion on all the time?
No. A well-insulated cylinder holds heat for hours; a timer is much cheaper.
Does the standing charge affect appliance running costs?
No. The electricity standing charge is a fixed daily fee you pay whether or not the appliance is on, so it is excluded from these figures.
Sources and methodology
Energy prices come from the Ofgem price cap for Direct Debit customers (GB average). Installation costs are typical UK ranges from installer quotes and industry guidance, rounded. Savings use today's rates and do not predict future prices.