How much does it cost to run a portable air conditioner per hour in the UK?

At the 2026 price cap of about 27p/kWh, a 9,000 BTU portable air conditioner costs roughly 27p an hour to run. Smaller 7,000 BTU units are around 22p; larger 16,000 BTU units around 49p.

Is it expensive to run a portable air conditioner all night?

No. An 8-hour night with a 9,000 BTU unit costs a little over £2 at current UK electricity prices. An inverter model run on a timer costs less.

Do portable air conditioners use a lot of electricity?

They draw around 1 kW per 9,000 BTU — similar to a microwave or a couple of old halogen heaters. Sizing the unit correctly and using an inverter model keeps consumption down.

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How much does it cost to run a portable air conditioner in the UK?

The honest answer: a few pence an hour for a small unit, more for a big one. Here is the maths at current UK prices, plus how to keep it down.

The number that scares people off portable air conditioning is the electricity bill — and it is usually less frightening than they expect. A portable AC's running cost comes down to two things: how many watts it draws, and what you pay per unit of electricity. Get those two numbers and the rest is arithmetic.

The quick formula

Running cost per hour = power (in kilowatts) × price per kWh. As a rule of thumb a portable AC draws roughly 1 kW for every 9,000 BTU of cooling. The 2026 Ofgem price cap puts a unit of electricity at about 27p per kWh, so:

Unit size	Approx. power	Per hour	8-hour night
7,000 BTU	~0.8 kW	~22p	~£1.75
9,000 BTU	~1.0 kW	~27p	~£2.16
12,000 BTU	~1.3 kW	~35p	~£2.81
16,000 BTU	~1.8 kW	~49p	~£3.89

So cooling a bedroom overnight with a 9,000 BTU unit is a little over £2 — comparable to leaving a few old halogen bulbs on. Run it every night across a two-week heatwave and you are looking at roughly £30, not the hundreds people fear.

Why inverter models cost less to run

Cheaper portable ACs are "fixed speed": the compressor is either flat out or off, cycling on and off to hold a temperature. Inverter models vary the compressor speed, so once the room is cool they tick over at low power instead of slamming on and off. Over a long evening that is quieter and noticeably cheaper. If you will use the unit for more than an hour or two at a time — and in a UK heatwave you will — an inverter is worth the premium. The Meaco Cirro range is inverter-driven, which is part of why it runs so quietly.

Five ways to cut the bill

Size it right. An undersized unit runs flat out and never catches up. Use our BTU calculator to match the unit to the room.
Seal the window kit. Most of the wasted energy is hot air leaking back in around the exhaust hose. A proper window seal makes a real difference.
Close curtains on the sunny side during the day so the room starts cooler.
Use the timer. Cool the room before bed and let it coast — you rarely need it running at full tilt all night.
Single hose vs dual hose. Dual-hose units are more efficient because they do not pull cooled room air out through the exhaust.

Is it cheaper than fixed air conditioning?

To run, no — a fixed split system is more efficient per unit of cooling. But a portable has no installation cost (a fitted system is £1,500+ installed) and you can move it room to room. For the handful of genuinely hot weeks the UK gets, a portable almost always wins on total cost.

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Figures are approximate and change with energy prices, stock and season. This guide contains affiliate links — we may earn a small commission at no cost to you, and it never affects what we recommend.