Air conditioning running cost calculator
Work out what your air conditioning costs per hour, per day and over the summer, with the maths shown so you can check it.
a day, about over
per running hour
per day
per week
The working:
A higher SEER means a cheaper unit to run; our running cost guide shows why efficiency and sizing matter, and our cost guide covers the upfront side.
How the maths works
Running cost is simple: the electricity the unit draws (kW), times the hours it runs, times your rate per kWh. The calculator builds on the unit's power input, never the cooling output, because a modern unit moves several units of heat for every unit of electricity it uses. If you only know the cooling capacity, it estimates the draw from the SEER efficiency figure on the energy label.
A typical home air conditioner draws somewhere between 0.5 and 2.5 kWh per hour, which works out at roughly 20p to 65p per hour at the current price cap. Inverter units rarely run at full power for long: once the room reaches temperature they throttle back, which is why the calculator applies a duty cycle rather than assuming full power all day.
The default electricity rate is the Ofgem price cap for 1 July to 30 September 2026, 26.11p per kWh. The cap changes every three months, with the next rate announced around 26 August 2026, so enter the rate from your own bill for an exact figure. The full method and cost tables are in our guide to whether air conditioners are expensive to run.
Running cost questions, answered
How much does it cost to run air conditioning per hour? +
Roughly 20p to 65p per hour for a typical home unit at the current price cap rate of 26.11p per kWh. The exact figure depends on the unit's power draw, its efficiency, the room and the temperature you set.
Is it cheaper to leave air conditioning on all day? +
No. Cooling an empty home is paying to fight heat nobody feels. Use the timer or a smart control so the unit starts shortly before you need the room. While it runs, an inverter unit holding a steady temperature is efficient, but running it all day for a room you use in the evening still costs more than running it for the evening.
Does a portable cost more to run than a split system? +
Yes. Portables are less efficient because warm air leaks back into the room through the exhaust hose, so they cost more per hour for less cooling. A fixed split is cheaper to run and more effective for a room you use regularly.
What do SEER and COP mean? +
Both measure efficiency: how much cooling you get per unit of electricity. COP is the instant figure and SEER is the seasonal average across realistic conditions. Higher is better in both cases. Modern UK splits commonly carry a SEER of around 6.5 to 8.5; look for 7 or above when buying.
Thinking about a fixed installation?
An efficient, correctly sized split system is the cheapest air conditioning to run. Compare quotes from local F-Gas registered installers.