Free tool · no sign-up
How much does it cost to run air conditioning?
Pick a unit size, how long it runs and its efficiency rating. The electricity price starts at the Ofgem price cap and you can change it.
Method last reviewed . Nothing you enter leaves your browser (privacy).
Cooling or heating?
On the unit's energy label. New units are often 6 to 8 (SEER) and about 4 (SCOP).
Units rarely run flat out. Half of rated output is a sensible start; hot spells in a sunny room run higher.
Default: 26.32p, the Ofgem price cap average for 1 October to 31 December 2026 (direct debit, standing charge not included). Use your own rate if you are on a fixed or time-of-use tariff. The next cap is announced 25 November 2026.
Roughly
5.4pan hour
Draws about 0.20 kW of electricity while running.
- A day
- 32p
- A month of use
- £9.71
- A year at this use
- £19.42
- Electricity a year
- 74 kWh
Show the sums
- Output while running: 2.5 kW × 50% = 1.25 kW
- Electricity drawn: ÷ 6.1 SEER = 0.20 kW
- Cost an hour: 0.20 kW × 26.32p = 5.4p
- A day: × 6 h = 32p. A year: × 60 days = £19.42
An estimate. SEER and SCOP are seasonal averages from lab tests; real use varies with weather, set temperature and how the room is used. Standing charges, and the cost of buying and installing the unit, are not included.
How the estimate works
An air conditioner moves heat rather than making it, so it delivers several units of cooling or heating for each unit of electricity it uses. The estimator takes the output you are using (the unit size multiplied by how hard it works on average), divides it by the efficiency (SEER for cooling, SCOP for heating) to find the electricity drawn, and multiplies by the price per kWh.
The default price is the Ofgem price cap average for 1 October to 31 December 2026: 26.32p per kWh, from Ofgem. That figure covers England, Scotland and Wales on default tariffs paid by direct debit, and it changes every three months. Because it does not include the standing charge, we leave that out too: the standing charge is paid whether or not you use the unit.
Cutting the bill
- Choose the right size. A unit sized to the room (try the size calculator) runs at its efficient part-load setting instead of cycling.
- Look at the energy label. A higher SEER means less electricity for the same cooling.
- Shade the windows. Blinds or external shading reduce the load before the unit starts.
- Have it serviced. A dirty filter or low refrigerant makes it work harder, and refrigerant work must be done by an F-gas certified engineer.
Ready to compare quotes? See the installers we have checked in Brighton & Hove.
FAQ