How Much Does It Cost to Run a Portable Air Conditioner? (UK 2026)

The Short Answer: What a Portable AC Costs to Run

Most UK portable air conditioners draw between 0.8 kW and 1.6 kW of electricity, depending on size (BTU). At the July 2026 Ofgem price cap of 26.11p per kWh, that works out to roughly 21p to 42p per hour of active cooling.

The formula every running-cost figure on this page is built on is simple:

Power (kW) × Electricity unit rate (p/kWh) = Cost per hour

So a 9,000 BTU unit pulling 1.0 kW costs 1.0 × 26.11 = 26.1p for every hour the compressor runs. Get your exact wattage from the rating plate or manual, multiply by your own unit rate (check a recent bill — regions vary), and you have a precise figure for your home.

Pence-Per-Hour Table by BTU

Portable units are sold by cooling capacity in BTU/h (British Thermal Units per hour). Higher BTU cools a bigger room but draws more power. The table below uses typical real-world power draw for each class and the 26.11p cap rate.

Cooling capacity	Typical power draw	Cost per hour	8-hour night	Per month*
7,000 BTU	~0.8 kW	~21p	~£1.67	~£25
9,000 BTU	~1.0 kW	~26p	~£2.09	~£31
12,000 BTU	~1.3 kW	~34p	~£2.72	~£41
14,000 BTU	~1.6 kW	~42p	~£3.34	~£50

Monthly figure assumes 8 hours' use per day for 30 days. Most households run AC only on hot days, so real seasonal spend is usually far lower.

An important honest caveat: these are maximum figures assuming the compressor runs flat-out the entire time. In practice, once your room reaches the set temperature the compressor cycles off and only the fan ticks over. Real-world consumption is commonly 20–40% lower than the headline numbers above. Treat the table as a worst-case ceiling, not a daily certainty.

How to Work Out Your Own Cost

1. Find the power rating. Look for "Power input," "Rated power," or watts (W) on the rating plate or in the manual. Divide watts by 1,000 to get kW (e.g. 990 W = 0.99 kW).
2. Find your unit rate. Check a recent electricity bill for pence per kWh. The cap average is 26.11p, but your region and tariff may differ.
3. Multiply. Power × rate = cost per hour. Multiply by hours used for daily cost.
4. Cross-check the BTU. If you're still shopping, our BTU calculator tells you the smallest capacity that will actually cool your room — and a right-sized unit is a cheaper-to-run unit.

How to Cut Your Running Costs

The single biggest lever is buying the right size in the first place. An oversized unit costs more to buy and more to run. After that, these tactics genuinely move the needle:

• Use eco / energy-saving mode. This caps compressor power and lets the fan do more of the work, trimming consumption noticeably on milder days.
• Run sleep mode overnight. Sleep mode gradually lets the temperature drift up by a degree or two as you fall asleep — you won't notice, but the compressor runs far less.
• Set a timer. Cool the room before bed, then let the timer switch off after a couple of hours. There's no point cooling an empty room till morning.
• Buy an A-rated, R290 unit. Energy-efficiency labels matter. An A-rated model with a higher EER (Energy Efficiency Ratio) delivers more cooling per kilowatt. Modern units using R290 (propane) refrigerant are typically more thermodynamically efficient than older R410A/R32 designs and carry a very low global-warming potential — a genuine win on both bills and environment.
• Seal the hose properly. Most portables vent hot air out of a window via an exhaust hose. A loose seal lets warm air leak back in, forcing the compressor to work harder. Use the supplied window kit and block gaps.
• Set a sensible target temperature. Every degree lower costs energy. Aim for around 23–24°C rather than chasing 18°C.

Browse the full range of portable air conditioners to compare energy ratings and refrigerant types side by side.

Portable AC vs a Fan: The Honest Comparison

A fan doesn't cool air — it moves it, helping sweat evaporate so you feel cooler. An air conditioner genuinely removes heat from the room. That difference shows up starkly in running costs:

Appliance	Typical power	Cost per hour (26.11p/kWh)	8 hours
Pedestal / tower fan	~0.05 kW (50 W)	~1.3p	~10p
9,000 BTU portable AC	~1.0 kW	~26p	~£2.09

A fan is roughly 20× cheaper to run — about a penny an hour. If you simply need air movement on a warm evening, a fan is unbeatable value. But on a genuinely hot, humid UK night (the kind we increasingly get in July and August), a fan just pushes warm air around. An AC is the only thing that will drop the actual room temperature and pull moisture out of the air.

Our take: keep a fan for mild days and use the portable AC for the handful of genuinely sweltering nights each summer. Over a typical UK summer of 20–40 hot nights, an AC adds roughly £40–£90 to your annual electricity bill — a modest sum for proper sleep during a heatwave.

What About Installation Costs?

Here's a real advantage of portables: there are none. A portable unit needs no F-Gas-registered engineer, no wall penetration, no planning permission and no fixed wiring. You unbox it, fit the window hose kit, and plug it into a standard socket. (Fixed split-system air conditioning is a different story — that does require a qualified F-Gas installer and, sometimes, planning consideration.) For renters and anyone wanting flexibility, the portable's zero install cost is a big part of its appeal.

If you're battling humidity as much as heat, also consider a dehumidifier — they're far cheaper to run and make a muggy room feel markedly more comfortable.