How much electricity does air conditioning use?

One simple sum tells you what your air con really costs.

The answer in 2 lines. How much an air conditioner uses depends on its electrical power, its efficiency and how many hours it runs. To estimate the cost: kWh used × the unit rate on your bill. From 1 October to 31 December 2026, Ofgem's price cap puts the average electricity unit rate at 26.32p per kWh for Direct Debit customers. Your own rate depends on your region, your tariff and how you pay. Portable units use much more energy than fans. Shading windows and closing doors cut running hours.

The first 3 steps

Find the power use on the energy label or in the manual: annual consumption in kWh per year and the SEER efficiency figure, or the power input in W or kW.
Find your unit rate on your electricity bill or app, in pence per kWh. If you have a peak and off-peak tariff, note both rates.
Estimate your hours: how many hours a day it runs, and on how many hot days a year.

Stop: danger

Burning smell, smoke, sparks or a hot plug: switch off at the wall only if it is safe to do so and unplug. If there is fire or smoke, get everyone out and call 999.
Water dripping onto a socket or the unit's plug: do not touch it with wet hands. Switch off at the consumer unit (fuse box) if it is dry and safe to reach.
Portable unit on an extension lead: follow the manual. A high-power appliance can overheat a lead, so plug it straight into a wall socket where the manual says to.

A worked example (made-up figures)

Step	Assumption	Result
Electrical power while running	A wall-mounted split unit drawing about 0.8 kW	0.8 kWh per hour
Use	4 hours a day, 40 hot days a year	160 hours
Consumption	0.8 × 160	128 kWh
Cost	128 × 26.32p (average cap rate, October to December 2026)	About £34 for the summer

The power and hours are made up for the example. Use your own unit's figures and the rate on your bill. Ofgem's cap figures are averages for England, Scotland and Wales, and Ofgem says they include no VAT on electricity from 1 October 2026 to 31 March 2027. The rate for January to March 2027 is due to be announced on 25 November 2026.

What pushes the cost up

A very low setting: the lower it is, the longer the unit runs.
Dirty filters, or an outdoor unit in full sun or blocked by clutter.
A room that is not closed off: an open window, or a door left open to a warmer room.
A portable unit: the Energy Saving Trust says portable units use much more energy than fans. If you use one, choose one the right size for the room and keep internal doors shut.
A unit too small for the room, running flat out all day.

What not to do

Comparing two units only on the energy class letter, without looking at the annual kWh shown on the label.
Leaving the air con running all day in an empty home.
Running the air con with the curtains open in full sun: shade first, then cool.

Check your own figures

Your regional rate: unit rates and standing charges vary by region and payment method. On Ofgem's regional rates page, pick your region and how you pay (Direct Debit, standard credit or prepayment). If you are on a fixed tariff, use the rate on your bill instead.
Your real use: with a smart meter, compare a hot day with the air con on and a similar day with it off, on your in-home display or your supplier's app. See our guide on reading a smart meter.

Use less without overheating

The Energy Saving Trust advises passive cooling first: close blinds and curtains while the sun is on the windows, and open windows at night or early in the morning when it is cooler outside.
Fans are the cheapest way to keep cool, even though they do not lower the room temperature. The NHS says fans work best when the temperature is below 35°C.
Clean the filters regularly (see our guide) and keep the outdoor unit clear.
Switch the unit off when you go out, and cool only the room you are using.

Good to know

On the energy label of a cooling unit, SEER is its efficiency over a whole cooling season: the higher it is, the less electricity it uses for the same cooling. The label also shows annual consumption in kWh per year.
A reversible air-to-air heat pump can also heat in winter. It has to be installed by a professional, and refrigerant work needs a qualified engineer.

In Bristol, Tom's electricity use jumps during a July heatwave. He does the sum: his portable unit ran 10 hours a day on its lowest setting. He moves his work into the cooler back room, closes the front curtains in the afternoons, runs the unit only in the evening with the door shut, and uses a fan the rest of the day. His smart meter shows the difference within a week.

A made-up story, for illustration.

Bobby

Sources, verification, confidence

Verified on 6 November 2026, for England. Confidence: high for the price cap rate, the VAT position and the next announcement date (Ofgem), and for the calculation method; medium for the example, whose power and hours are made up. There is no recent official figure for the average consumption of home air conditioners in England. Your exact rate is the one on your bill.