How much does a microwave cost to run per hour, and per reheat?
A solo microwave pulls around 1,300 watts from the socket, which is 33.9p an hour at the Ofgem cap rate of 26.11p per kWh. Almost nobody runs one for an hour though, and the number that matters is 2.8p for a five minute reheat or 1.7p for three minutes.
The wattage on the door is not the wattage you pay for
Every guide to microwave running costs starts by asking how many watts your microwave is, and most of them then use the wrong number. The 800 watts or 900 watts printed on the door or in the manual is the cooking power the magnetron delivers into the cavity. It is not what comes out of the socket.
A magnetron is around 71 per cent efficient across the 203 models in the largest published survey, and the turntable motor, the fan and the control board all draw on top. That is why an 800 watt solo microwave typically pulls 1,100 to 1,300 watts from the wall, and why the fuse in the plug is 13 amps rather than 5. Bosch makes the gap plain on its own spec sheets, where the Series 8 combination oven lists a maximum microwave power level of 800 watts against a connection rating of 3,600 watts.
For costing we use 1,300 watts as the everyday figure for a solo microwave, with 1,000 watts for a small 600 watt output model and 2,200 watts for a large combination unit with a grill. Your own plate will give you the exact number, and the calculator takes it.
Work it out for your own microwave
Type in the wattage from the plate on the back, then your own unit rate. The numbers update as you type.
What an hour costs, and what a reheat costs
At 1,300 watts an hour of continuous running uses 1.3 kilowatt hours, which is 33.9p at the Ofgem cap rate of 26.11p per kilowatt hour. That is the figure the search results want, and it is close to useless, because a microwave running for a solid hour is a microwave with something badly wrong in it.
Per minute the draw is 0.0217 kilowatt hours, or 0.57p. One minute costs 0.6p. Two minutes cost 1.1p. Three minutes, which is a bowl of soup or a plate of last night's dinner, costs 1.7p. Five minutes costs 2.8p. Ten minutes, enough for a jacket potato, costs 5.7p. Half an hour of defrosting and cooking costs 17p.
A household that reheats twice a day for five minutes gets through 6.6 kilowatt hours a month, which is £1.71. For readers in the United States the EIA residential average of 18.34 cents per kilowatt hour puts the hour at about 24 cents and the five minute reheat at about 2 cents.
| Appliance | Typical draw | Usage we assume | Per hour (UK) | Per usage (UK) | Per month (UK) | Per hour (US) |
|---|---|---|---|---|---|---|
| Microwave | 1300 W | per 5 minute reheat | 33.9p | 2.8p | £1.71 | 23.8 cents |
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.
The clock costs more than you would guess
The standby regulations cap a device with a lit display at 1.00 watt, and a microwave with a clock on the front is exactly that. One watt for all 8,760 hours of the year is 8.76 kilowatt hours, or £2.29.
Set that next to the cooking. Two five minute reheats a day for a year is around 79 kilowatt hours and £20.65, so the clock is adding roughly a ninth on top for the privilege of telling you a time that is also on your phone, your oven and your cooker hood. It is not a large number in absolute terms, and it is the only running cost in this article you can remove entirely by pulling a plug.
Against the oven, the hob and the air fryer
Reheating is the one job where the microwave is untouchable, and the reason is that it heats the food rather than the box. An electric oven uses about 0.87 kilowatt hours for a standard cycle on the energy label, 22.7p, before you count the ten minutes of preheating that produced no food at all. A five minute microwave reheat costs 2.8p. The oven is eight times the price for a worse result on anything wet.
Against an air fryer the gap narrows and then reverses. A 1,750 watt air fryer running a 25 minute cook uses 0.735 kilowatt hours and costs 19.2p, which is seven reheats worth of electricity. For warming a plate of leftovers the microwave wins by a distance. For chips, chicken thighs or anything that needs a crust, the air fryer is the only one of the two that can do the job, so the comparison stops being about money.
The kettle is the outlier. A three minute boil in a 3 kilowatt kettle uses 0.15 kilowatt hours and costs 3.9p, and that is the price of a full kettle even on a morning when you only wanted one mug. Heating a single mug in the microwave for two and a half minutes uses 0.054 kilowatt hours and costs 1.4p, so the microwave genuinely is cheaper for one cup. It is also slower, and it will not do a teapot, which is why the sensible rule is to fill the kettle to the line you need rather than to swap appliances.
Five ways to spend less at the microwave
- Cover the bowl. Trapped steam heats the food from all sides, which typically cuts a reheat by a third and cuts the cost by the same third.
- Stir once halfway through rather than adding another two minutes at the end, because cold spots are a distribution problem rather than a power problem.
- Stop using the defrost setting for things you could plan ahead for, since defrost runs the magnetron in bursts for fifteen or twenty minutes to do what a fridge shelf does overnight for nothing.
- Match the container to the food. A wide shallow dish reheats faster than a deep narrow one, and the difference is minutes rather than seconds.
- Pull the plug at the socket if the microwave is the second one in the house or lives in a utility room, and take the £2.29 a year that the clock was costing you.
Common questions
How much does it cost to run a microwave for 10 minutes?
About 5.7p. Ten minutes at 1,300 watts input is 0.217 kilowatt hours, which is 5.66p at the current cap rate. Two minutes costs 1.1p, three minutes costs 1.7p and fifteen minutes costs 8.5p.
Does a microwave use a lot of electricity on standby?
The clock and the touch panel are capped at 1.00 watt by the standby regulations, which is 8.76 kilowatt hours and £2.29 across a full year. That is more than a television costs on standby, and for a household that reheats twice a day it is around a tenth of what the microwave costs to actually use.
Is it cheaper to use a microwave or an air fryer?
The microwave, for reheating. A five minute reheat costs 2.8p against 19.2p for a 25 minute air fryer cook. The air fryer wins on anything that needs to come out crisp, because the microwave cannot do that job at any price.
Why does my 800 watt microwave draw 1,300 watts?
The number on the door is the cooking power delivered to the food. The magnetron that produces it is roughly 71 per cent efficient, so the input from the socket is always higher. Use the input figure from the plate on the back for cost, and the output figure for recipe timings.