How Much Does It Cost to Run a Portable Air Conditioner in the UK? (2026)
A portable air conditioner costs roughly 21p to 37p an hour to run in the UK at the current July 2026 electricity rate of 26.11p per kWh — about £1.70 to £2.90 for an eight-hour night, or £50 to £88 a month if you run it eight hours a day. The exact figure comes down to a single number: how much power the unit draws, measured in kilowatts. Here’s how to work out your own running cost, what different sizes cost, how it stacks up against a fan, and the simple ways to bring the bill down.
How much does it cost to run a portable air conditioner in the UK?
The maths is genuinely simple, because running cost is just power multiplied by price:
Power of the unit (in kW) × price per kWh = cost per hour.
The price is set by the Ofgem energy price cap, which from 1 July to 30 September 2026 puts the average electricity unit rate at 26.11p per kWh (for a standard variable tariff paid by Direct Debit, including VAT). Most portable air conditioners draw somewhere between 0.8 and 1.4 kW depending on their size and how hard they’re working. So a 1 kW unit costs 1 × 26.11p = about 26p an hour, and the range across typical units works out to roughly 21p to 37p an hour. To find your exact number, check the wattage on the unit’s label or manual, divide by 1,000 to get kilowatts, and multiply by your own electricity rate.
What do different sizes cost to run?
Because bigger units pull more power, the cost climbs with cooling capacity (BTU). Crucially, this only holds if the unit is sized correctly for the room — an undersized one runs flat out without ever cooling the space, which costs more, not less. Here’s the full picture per hour, per eight-hour night, and per month if you run it eight hours a day:
| Unit size | Power | Per hour | Per night (8 hrs) | Per month (8 hrs/day) |
|---|---|---|---|---|
| ~7,000 BTU (small) | ~0.8 kW | ~21p | ~£1.67 | ~£50 |
| ~9–10,000 BTU (medium) | ~1.0 kW | ~26p | ~£2.09 | ~£63 |
| ~12,000 BTU (large) | ~1.2 kW | ~31p | ~£2.51 | ~£75 |
| ~14,000 BTU (XL) | ~1.4 kW | ~37p | ~£2.93 | ~£88 |
The monthly figures assume you run it every single day, which most UK homes won’t — our weather tends to deliver heat in short bursts rather than constant summer warmth. On genuinely hot spells, budgeting a couple of pounds a night is realistic. To choose a unit sized right for your room (and see what each costs to run), our guide to the best portable air conditioners in the UK breaks it down, and the interactive portable AC comparison tool lets you filter by room size and running cost.
Is a portable AC more expensive to run than a fan?
Yes — considerably. A typical tower or pedestal fan draws only about 50 watts, which at 26.11p per kWh costs roughly 1.3p an hour, or about 10p for a whole eight-hour night. A portable air conditioner running at 1 kW costs around 26p an hour, or £2.09 a night. That makes the air conditioner roughly 20 times more expensive to run than a fan.
The catch is that they don’t do the same job. A fan only moves air around — it doesn’t lower the room temperature or remove moisture, so on a humid heatwave night it just pushes warm, damp air past you. A portable AC actively cools and dehumidifies, which is what you need when it’s genuinely hot and sticky. The smart approach is to use a cheap fan for mild warmth and save the air conditioner for the nights that really need it. If a fan will do, our roundup of the best tower fans for the UK covers the cheapest options to run.
What makes a portable AC cost more (or less) to run?
Five things move the number up or down. Size and BTU is the biggest: a 14,000 BTU unit simply draws more power than a 7,000 BTU one. Energy efficiency matters too — a unit with a better energy rating (look for A or A+ and a higher EER) gets more cooling from each unit of electricity, often around 10% less consumption than a basic model. How hard it’s working depends on the room: a large, sunny or poorly-insulated space forces the compressor to run longer. Hours of use is the lever you control most directly — running it for three hours in the evening costs a fraction of leaving it on all day. And your tariff and region set the price itself: 26.11p is the national average cap rate, but a cheaper fixed tariff, a lower-cost region like London, or off-peak hours can all reduce it, while prepayment meters pay a little more. It’s also worth remembering single-hose units pull replacement air into the room, so a well-sealed window hose helps them work efficiently.
How do I cut the running cost?
The good news is that most of the savings are easy and free. Size the unit to your room so it isn’t running flat out or oversized; seal the window kit tightly around the exhaust hose so warm air can’t leak back in; and use the timer and sleep mode to cool the room down and then ease off rather than blasting all night. During the day, close curtains and blinds on sunny windows, and only cool the room you’re actually in by shutting the door. Set a sensible temperature too — 22–24°C is comfortable and far cheaper than 18°C, since every degree higher cuts consumption by roughly 3%. And lean on a fan whenever the heat is only mild, keeping the air conditioner for the hot, humid nights that justify it.
The bottom line
Running a portable air conditioner in the UK costs about 21p to 37p an hour at the July 2026 rate of 26.11p per kWh — roughly £1.70 to £2.90 a night, or £50 to £88 a month with heavy daily use. Work out your own figure by multiplying the unit’s kilowatts by your electricity rate, remember it’s around 20 times pricier to run than a fan, and keep the bill down by sizing it right, sealing the hose, using a timer and saving it for the nights that genuinely need cooling. For help choosing a unit, see our guide to the best portable air conditioners in the UK.
Running costs are estimates based on the Ofgem price-cap average electricity rate from July 2026 (26.11p/kWh) and assume typical power draws; your actual cost will vary by unit, tariff, region, payment method, insulation and how you use it. Check your latest bill for your own unit rate.