Portable air conditioner · current figures
Last updated 2026-06-24~30p
an hour to run
~£2.40
an 8-hour day
1,200W
typical unit power
24.67p
per kWh (price cap)
Electricity rate: Ofgem price cap, 1 April to 30 June 2026, Direct Debit (Ofgem). A 1,200 W portable for one hour uses 1.2 kWh, which is about 30p. Costs scale with the wattage on the rating plate.
How much does a portable air conditioner cost to run?
The sum is the same one that prices every appliance: power × time × your rate. A portable air conditioner pulls between about 780 W and 1,600 W depending on its size, so at the 24.67p price cap a single hour costs roughly 19p to 39p. The table shows the common sizes, by the wattage on the rating plate and the BTU on the box.
Portable AC running cost by size
at 24.67p/kWh| Size | Power | Per hour | 8-hour day | Hot fortnight |
|---|---|---|---|---|
| 7,000 BTU | ~780 W | ~19p | ~£1.54 | ~£22 |
| 9,000 BTU | ~990 W | ~24p | ~£1.95 | ~£27 |
| 12,000 BTU | ~1,300 W | ~32p | ~£2.57 | ~£36 |
| 14,000 BTU | ~1,600 W | ~39p | ~£3.16 | ~£44 |
A "hot fortnight" here means running the unit eight hours a night for 14 nights, the kind of spell a UK summer now serves up. Use it more sparingly and the cost drops in proportion. But these figures assume the unit delivers all its cooling, and that is exactly where the single-hose design lets you down.
What does your portable really cost, and how much cooling do you actually get?
Set your unit's power, hours and hose type. We show the running cost and how much of the cooling actually reaches your room.
A hot fortnight costs
Per hour
A day
Cooling that reaches the room
Costs at the 24.67p price cap. The "cooling reaches the room" figure reflects the negative-pressure loss of a single-hose design (roughly 30% in a typical room) versus a sealed dual-hose unit. Indicative, not a lab measurement — June 2026.
The belief that costs people money
Most people buy a portable air conditioner on one number: the BTU on the box. Higher BTU, more cooling, job done. But BTU is the cooling the machine can produce in a lab, not the cooling your room actually receives. With a single-hose unit, a slice of that cooling is cancelled out the moment you switch it on, by the unit's own design. So two 9,000 BTU portables can leave one room pleasantly cool and another barely changed, with no fault in either machine.
The second costly belief is that a portable is "the cheap option". It is cheap to buy. To run, it is the most expensive type of air conditioning per hour of real cooling, precisely because so much of its output leaks away. Cheap on the shelf, dear in the room.
Why most portable AC reviews get it wrong
Open a typical "best portable air conditioner" round-up and you will see units ranked by BTU, price and star rating. What you almost never see is the hose count, even though it changes the real-world performance more than a couple of thousand BTU does. The reviews quote the cost per hour from the wattage, which is fair, but they ignore that a single-hose unit has to run longer to reach the same temperature, so its real cost per degree cooled is higher than the headline 30p an hour suggests.
That is the gap this guide fills: not just what the unit draws, but how much of that you actually feel. Put your own wattage and hose type into the calculator above to see both numbers at once.
The insider truth: the single-hose trap
Here is the mechanism nobody explains. A single-hose portable takes air from your room, cools you with part of it, and blows the warm exhaust out of the window through its one hose. But that air has to come from somewhere. As the unit pumps room air outside, it creates a faint vacuum, and the room refills itself by pulling outdoor air in through every gap: under doors, around the window seal, through the floor. On a hot day, that incoming air is hot. So the unit is partly cooling air that it itself just dragged in from outside.
Why two hoses fix it A dual-hose unit takes the air it needs for its exhaust from outside, through a second pipe, instead of stealing it from the room. The room stays sealed, there is no vacuum, and no hot air is pulled in. You get close to the full cooling you paid for. The catch: dual-hose models are rarer and a little pricier, so most shoppers never see the option. If you are buying a portable you will use a lot, seek out a dual-hose model — it is the single biggest upgrade to real-world cooling you can make, and it cuts run time, which cuts cost.
If you are stuck with a single-hose unit, you can claw some of the loss back: seal the window kit well, shut internal doors so the vacuum pulls from a smaller space, and run the unit in the room you are actually in rather than trying to cool the whole floor. None of this beats a second hose, but it narrows the gap.
Your portable air conditioner's running cost, at your rate
Costs you about
a year · · £
Each
A month
Cheapest live electricity rate
British Gas is offering 23.85p per kWh — about 9% below the 26.11p price cap. Apply it to see every cost above drop.
A lower unit rate cuts the cost of every appliance above at once.
Default unit rate: Ofgem price cap, 1 July to 30 September 2026, Direct Debit. Costs are estimates based on typical power ratings.
Every appliance at a glance
at the 26.11p/kWh price cap| Appliance | Power | Typical use | kWh/yr | Per use | Per year |
|---|---|---|---|---|---|
| Air fryer | 1,500 W | 30 min, 5×/wk | 195 | 19.6p | £51 |
| Electric oven | 2,100 W | 60 min, 5×/wk | 546 | 54.8p | £143 |
| Broadband router | 10 W | all day, 7×/wk | 87 | 6.3p | £23 |
| TV (50-inch LED) | 90 W | 300 min, 7×/wk | 164 | 11.7p | £43 |
| Tumble dryer | 2,500 W | 90 min, 3×/wk | 585 | 97.9p | £153 |
| Washing machine | 1,000 W | 60 min, 4×/wk | 208 | 26.1p | £54 |
| Dishwasher | 1,200 W | 90 min, 4×/wk | 374 | 47.0p | £98 |
| Kettle | 3,000 W | 3 min, 21×/wk | 164 | 3.9p | £43 |
| Fridge-freezer | 17 W | all day, 7×/wk | 149 | 10.7p | £39 |
| Electric heater | 2,000 W | 240 min, 7×/wk | 2,912 | £2.09 | £760 |
| Electric fan | 50 W | all day, 7×/wk | 437 | 31.3p | £114 |
| Portable air conditioner | 1,200 W | 240 min, 7×/wk | 1,747 | £1.25 | £456 |
| Split air conditioner | 750 W | 240 min, 7×/wk | 1,092 | 78.3p | £285 |
| Electric shower | 8,500 W | 10 min, 7×/wk | 516 | 37.0p | £135 |
| Desktop / gaming PC | 200 W | 240 min, 7×/wk | 291 | 20.9p | £76 |
All figures at the Ofgem price-cap electricity rate of 26.11p per kWh (1 July–30 September 2026, Direct Debit). Standing charges are paid whether or not you switch anything on, so they are not included here. Change the rate in the calculator above to re-price every row for your own tariff. The cheapest live electricity rate we can see today is 23.85p per kWh from British Gas, about 9% below the cap; at that rate every cost above falls by roughly the same share.
When a fan or a fixed unit beats a portable
A portable is the right tool only in a narrow band. Below it, a fan does the job for pennies; above it, a fitted system does it better and cheaper per hour.
- ✓A fan wins when you just need moving air. At under 2p an hour it costs a fraction of a portable, and for mild UK warmth it is often all you need. See keeping cool in a heatwave for the cheapest options.
- ✓A fitted split wins when you cool a room often. It runs at roughly half the cost per hour, is far quieter, and heats in winter too. Our air conditioning units guide compares the full range.
- ✓A portable wins only for occasional cooling in a room you cannot or will not fit a unit into, such as a rented flat. That is its real niche.
What you should actually do
Check the hose count first
Before BTU, before price, before brand. A dual-hose unit gives you far more real cooling for the same electricity. Most shoppers never look — you now will.
Size it properly, then a touch bigger
A single-hose unit underdelivers, so do not undersize. Use the size finder on our air conditioning guide and round up if it is single-hose.
Seal the window kit
Whatever you buy, a leaky window seal lets hot air straight back in. A tight seal is free cooling you have already paid for.
Cut your unit rate
Every hour of cooling is priced at your electricity rate. A cheaper rate per kWh shrinks the run cost of the AC and everything else you own.
The bottom line
A portable air conditioner costs about 30p an hour, or £30 to £50 over a hot fortnight, and that is the easy part to plan for. The harder part is that a single-hose unit, the kind most people buy, quietly throws away around a third of its cooling by pulling hot air back into the room as it vents. Buy dual-hose if you can, size it generously if you cannot, seal the window kit either way, and remember a portable only earns its place for occasional cooling: a fan is cheaper for mild days, a fitted split cheaper to run for heavy use. As ever, the biggest lever on the bill is the rate you pay per kWh.
Portable air conditioner FAQ
The Selectra expert answers your questions
About 30p an hour for a typical 1,200 W (9,000 to 12,000 BTU) portable air conditioner, at the 2026 price-cap rate of 24.67p per kWh. That is roughly £2.40 for an eight-hour day, or about £30 to £50 over a hot fortnight of nightly use. A smaller 780 W unit is nearer 19p an hour; a big 1,600 W one nearer 39p.
More than most appliances, because they run for hours and cooling is hard work. A 1,200 W portable on for eight hours uses about 10 kWh a day, similar to running an electric oven for nearly five hours. They are not cheap to run, which is why a fan (under 2p an hour) is far better for mild warmth, and a fitted split is better for heavy use.
A dual-hose unit is more efficient. A single-hose model creates a slight vacuum as it blows warm air out, which pulls hot air back into the room through gaps, so it has to work harder and cools less. A dual-hose unit draws its exhaust air from outside instead, keeping the room sealed. If you can find one, dual-hose gives you more real cooling for the same electricity.
About 20 BTU per square foot of floor. A small bedroom (around 10 m²) needs roughly 7,000 BTU; an average living room (around 20 m²) needs about 10,000 to 12,000 BTU. Remember a single-hose unit delivers less than its rating in practice, so do not undersize. See our air conditioning size finder to get your exact number.
Cheaper to buy (£250 to £600 versus £1,500-plus fitted), dearer to run. A portable costs about 30p an hour; a fitted split does the same job for roughly 15 to 20p because it is a heat pump that moves heat efficiently. If you only cool a room a few weeks a year, the portable wins overall. If you use it often, the fixed unit pays back.