Air conditioning running cost calculator

Work out your running cost

Pick what the unit will do and its size, then add your hours, days and price. The calculator gives a low and a high figure, because a unit eases off once the room is comfortable.

The 6 hours and 30 days are examples, as we found no public figure for how much UK homes use air con. Change them to suit you.

Running costs at a glance

A 2.5 kW wall unit costs about 16p an hour at full power, at today’s capped price. These estimates use typical power for each size:

Your own unit may use more or less, so check its label. The price leaves out the standing charge, which you pay anyway.

Sources: Ofgem’s price cap, 1 October to 31 December 2026, at 26.32p per kWh, and 30 makers’ data sheets.

A fitted unit against a portable

A fitted unit uses less electricity than a portable for about the same cooling. These estimates compare one of each:

Treat this as a guide, because the two are tested at different room temperatures. A portable also needs a hose out of a window. Options with no fitting.

Sources: Meaco’s MC Series specification sheet, and the energy label rules for the tests.

Heating with air con against other heating

Air con can cost less than plain electric heaters, and about the same as gas in a real home. The cost of 1 kWh of heat, at today’s capped prices, is:

The rated figure comes from a test lab, while the gas figure comes from real homes. The fair match is real-world against real-world, and there the two are about level. The government’s review says heat pumps don’t generally bring big savings against gas. Air-to-air heat pumps explained.

Sources: Ofgem’s price cap, the government’s boiler assessment and its air-to-air review.

How the calculator works

The calculator multiplies the unit’s power by your hours, your days and your price:

1. It takes typical full-power use for the size, from 30 wall units on makers’ data sheets.
2. It multiplies that by your hours a day and days a year.
3. It multiplies that by your price per kWh.
4. It halves the answer for the low figure.

The half comes from the makers’ lab figures, which suggest about half over a season. A unit can also draw more than its rated power for a short spell. The government’s review found no measured yearly figures from UK homes, so treat both figures as estimates.

What pushes the cost up or down

The set temperature and the fan speed change the cost most, among the things you control:

• Set temperature: Daikin and Panasonic suggest 26 to 28°C for cooling and 20 to 24°C for heating.
• Fan speed: Samsung says a higher temperature and a slower fan save energy.
• Eco settings: these limit the power, in a different way on each make.
• Size: a unit that’s too small runs flat out for longer.
• Windows: keep them shut while it runs. What an open window costs.

Which mode to use, and how to find the right size.