How much does it cost to run an electric shower for an hour, and per shower?
An 8.5 kilowatt electric shower costs £2.22 for a full hour at the current Ofgem cap rate of 26.11p per kWh, and a normal eight minute shower comes to 29.6p. A 7.5 kilowatt unit costs £1.96 an hour and a 10.8 kilowatt unit costs £2.82, because the cost tracks the rating on the front of the shower and nothing else.
What the number on the front of the shower means
An electric shower is the most honest appliance in the house. It has one job, it draws its full rating the entire time it is running, and the rating is printed on the fascia. Mira sells the same unit at 7.5, 8.5, 9.0, 9.5, 9.8 and 10.8 kilowatts, and those numbers are the whole story.
That makes the arithmetic simple. A kilowatt rating multiplied by hours gives kilowatt hours, and kilowatt hours multiplied by the unit rate gives the cost. No cycling, no standby, no label test conditions to argue about.
It also explains why an electric shower feels weak in winter. The element can only lift so much heat into the water, so when the mains supply drops from summer warmth to a few degrees the shower holds the temperature by cutting the flow instead. An 8.5 kilowatt unit lifting cold mains water by thirty degrees can deliver roughly four litres a minute, which is about half what a mixer shower gives you.
The sum, worked in full
Take the 8.5 kilowatt model. One hour is 8.5 kilowatt hours, and at the Ofgem cap rate of 26.11 pence that is £2.22.
Nobody showers for an hour, so divide it down. Eight minutes is 8.5 multiplied by 0.133 hours, which is 1.13 kilowatt hours, or 29.6p. One shower a day comes to £9.01 a month and £108.01 a year. A household of four taking the same eight minutes each runs to £36.03 a month, and that is the figure worth staring at.
Work it out for your own electric shower
Type in the wattage from the plate on the back, then your own unit rate. The numbers update as you type.
Cost by shower length and by rating
| Time | 7.5 kW | 8.5 kW | 10.8 kW |
|---|---|---|---|
| 5 minutes | 16.3p | 18.5p | 23.5p |
| 8 minutes | 26.1p | 29.6p | 37.6p |
| 10 minutes | 32.6p | 37.0p | 47.0p |
| 15 minutes | 49.0p | 55.5p | 70.5p |
| 20 minutes | 65.3p | 74.0p | 94.0p |
| A full hour | £1.96 | £2.22 | £2.82 |
| Appliance | Typical draw | Usage we assume | Per hour (UK) | Per usage (UK) | Per month (UK) | Per hour (US) |
|---|---|---|---|---|---|---|
| Electric shower | 8500 W | per 8 minute shower | £2.22 | 28.9p | £8.75 | $1.56 |
Rates: Ofgem cap 1 July to 30 September 2026 at 26.11p per kWh (source), EIA residential average June 2026 at 18.34 cents per kWh (source). Checked 2026-09-22.
Two points about that table. The daily standing charge is left out of every figure, because you pay it whether you shower or not, and the rating is what the shower draws rather than what it delivers. Almost all of the energy ends up in the water, which is why an electric shower is close to a hundred per cent efficient at the point of use and still expensive, since the electricity itself costs more than three times what gas costs.
In the United States the same 8.5 kilowatt unit costs $1.56 an hour at the EIA residential average of 18.34 cents per kilowatt hour, and 20.8 cents for an eight minute shower. Electric showers of this type are rare on a 120 volt supply, so the figure is mostly useful for readers with a tankless electric water heater, which is the same idea wearing a different badge.
Five ways to cut what the shower costs
- Take two minutes off. On an 8.5 kilowatt unit that saves 7.4p every time, which is £27.00 a year for one person and over a hundred pounds for a family of four.
- Fit a shower timer or play two songs, whatever keeps you honest. The only variable you control on an electric shower is the clock.
- Turn the power setting down in summer. Most units have a high and a low setting, and in July the mains water is warm enough that low gives a comfortable shower for two thirds of the cost.
- Descale the shower head. Blocked holes make the spray feel thin, and the usual response is a longer shower rather than a repair.
- Do not run a bath to top up a weak shower. A bath holds far more hot water than eight minutes under any shower head, electric or not.
- Think twice before replacing a working 8.5 kilowatt unit with a 10.8 kilowatt one. The bigger shower gives a better flow and costs 27 per cent more every minute it runs, so the upgrade shows up on the bill within weeks.
Electric shower against the combi boiler
Per unit of heat, gas is the cheaper fuel. The cap rate is 7.33 pence per kilowatt hour for gas against 26.11 pence for electricity, so heating the same water with a boiler costs roughly a third as much even after the boiler throws some of it up the flue.
The numbers are closer than that sounds, because the two showers do not deliver the same thing. Eight minutes under a mixer at ten litres a minute lifts eighty litres by thirty degrees, which is 2.79 kilowatt hours of heat, and at the gas rate with boiler losses that is about 24.1p. Eight minutes under the electric shower is 29.6p. The gas shower wins, but only by about a fiver a year per person, and it used two and a half times more hot water to do it.
The case for an electric shower was never the running cost. It is that it works when the boiler is off, it heats only what you use, and it costs nothing to leave idle all summer. If your household showers quickly the electric unit holds its own. If somebody in the house treats the shower as a place to think, gas is the cheaper habit to feed.
Common questions
How much does it cost to run an electric shower for 10 minutes?
An 8.5 kilowatt shower uses 1.42 kilowatt hours in ten minutes, which is 37.0p at the cap rate of 26.11p per kWh. A 7.5 kilowatt unit costs 32.6p for the same ten minutes and a 10.8 kilowatt unit costs 47.0p.
How much does it cost to run an electric shower for 15 minutes?
Fifteen minutes on an 8.5 kilowatt shower is 2.13 kilowatt hours, or 55.5p. Twenty minutes is 74.0p and half an hour is £1.11, so a long shower on an electric unit costs more than a full load in the washing machine.
How much does an electric shower cost per minute?
An 8.5 kilowatt shower costs 3.7p a minute at the current cap rate. The quick way to work out any model is to take the kilowatt rating, multiply by 26.11 and divide by sixty, which gives pence per minute.
Is it cheaper to run a gas or electric shower?
Gas is cheaper per unit of heat, at 7.33p per kilowatt hour against 26.11p for electricity, so a mixer shower fed by a gas combi usually wins. The catch is flow. A mixer at ten litres a minute pours far more hot water than an electric shower at four, so a short electric shower can still beat a long gas one.