Portable air conditioner running cost UK calculator

Work out your portable air conditioner running cost in the UK per hour, day, week and month at the Ofgem price cap rate of 26.32p/kWh. Free and editable.

By Matthew Smart · Rates correct as of 5 October 2026

Hi, I’m Matthew Smart. Of all the appliances I cover, the portable air conditioner is the one people worry about most when the bill arrives, and with good reason. This calculator works out your portable air conditioner running cost in the UK, per hour, day, week and month, at the current Ofgem rate.

A coffee machine heats water for a minute or two. A typical 1kW portable AC can run flat out for six hours on a hot afternoon, day after day through a heatwave, and that adds up to real money. Put your own figures in below and you will know what you are signing up for before the summer starts.

The biggest lever is time on full power: the cost is almost entirely hours multiplied by power, so cutting your daily runtime saves more than anything else. Cool the room down, then let the unit cycle or switch it off, rather than leaving it on full all day.

How to use it

1Enter the power draw from the rating plate in kilowatts, not the BTU figure. Most 9,000–10,000 BTU units draw about 1kW; a 12,000 BTU unit is nearer 1.35kW.
2Set how many hours a day you actually run it. Six hours is a typical UK summer pattern: an afternoon and evening during a hot spell, not all day, every day.
3Leave the rate at 26.32p/kWh (the Ofgem Energy Price Cap from 1 October) or type the rate from your own bill.

Portable air conditioner running cost UK calculator

Enter your unit’s power draw in kW (it is on the rating plate or in the manual, listed as input power), how long you run it each day and your electricity rate. The figures update as you type.

Unit power draw(kW)

Input power from the rating plate or manual. 1.0kW is typical for a 9,000–10,000 BTU unit; 16,000 BTU models draw about 1.7kW.

Hours used per day(hours)

Six hours is a typical UK summer pattern: afternoon and evening on a hot day.

Your electricity rate(p/kWh)

Pre-filled with the Ofgem Energy Price Cap unit rate for 1 October – 31 December 2026. Change it to the rate on your own bill.

Your estimate

Per hour1.00 kWh an hour at full power: 26.3p
Per day: £1.58
Per week: £11.05
Per monthBased on a 30-day month: £47.38

Assumes 1kW drawn for 6 hours a day at 26.32p per kWh (Ofgem Energy Price Cap, 1 October – 31 December 2026). Rates correct as of 5 October 2026.

What this figure does and does not cover

This is the cost of the unit drawing its full rated power for every hour you enter, so treat it as a well-informed estimate rather than a meter reading. Once the room reaches the temperature you have set, the compressor cycles off and the unit drops to fan-only power, so in a well-sealed room with a correctly sized unit your real bill is usually lower, often by 30–40%. An undersized unit in a large or sunny room may run flat out the whole time, and for that the figure is close to the truth.

How to read your estimate

Your weekly and monthly totals assume you use the unit the same way every day and that the electricity rate you entered stays unchanged. Real summers come in spells, so a cool July costs far less than a heatwave fortnight, and Ofgem rates and individual tariffs can change, so your actual costs may be higher or lower.

Rates correct as of 5 October 2026. Updated each time the price cap changes.

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