The Best Portable Air Conditioner (UK, 2026)

Before you spend £250 to £900, be honest about how many genuinely hot days you get. A portable AC is a big, heavy appliance that lives in a corner for ten months a year. Our quick decision guide:

• Hot for under 10 days a year? A good tower fan and closed curtains during the day will get you through. Do not buy a portable AC; it is £300+ of regret.
• Hot for 10 to 30 days, renting, or budget under £500? A portable AC is the right call, and this guide is for you.
• Hot for 30+ days, own your home, and can mount an outdoor unit? Price up a split system instead, typically £1,500 to £3,500 installed. It is around half the running cost, a third of the noise, lasts twice as long, and heats in winter. A portable is fighting physics; a split system is not.

Reading this in autumn or winter? You are actually in the best position of anyone: skip ahead to our when to buy section, because the smart money purchases in March.

BTU (British Thermal Units) measures cooling power, and both directions of wrong are expensive. Too small and the room never gets there while the unit runs flat out. Too big and it short-cycles: cools the air fast, shuts off before it has dehumidified, and leaves you in a room that is cold but clammy.

The working rule for a standard UK room with 2.4 m ceilings is 500 to 600 BTU per square metre. So a 12 m² bedroom wants around 7,000 BTU, an 18 m² lounge wants 9,000 to 10,000, and only genuinely large or open-plan spaces justify 12,000 and up. Add a size step for south-facing rooms, top floors, and anywhere with a lot of glass.

One more adjustment the listings never mention: nearly every portable sold in the UK is single-hose, and single-hose units deliver meaningfully less cooling than the box claims (the physics is in our hose section below). The practical takeaway is to buy one size up from your calculation. If the maths says 8,000 BTU, buy 9,000 or 10,000.

At the current Ofgem price-cap rate of 26.32p per kWh (Direct Debit, October to December 2026), the units on this list cost roughly 21p to 41p per hour at full power. Run one for eight hours on a hot night and that is £1.70 to £3.30. Over a typical UK summer of 20 to 40 hot nights, budget £40 to £90 for the season for a mid-size unit.

Two things soften that number in practice. First, portables do not run flat out continuously: once the room hits your target temperature the compressor cycles off and only the fan runs, so real-world costs typically land 20 to 40% below the headline figure. Second, the timer is your friend: outdoor temperatures fall naturally after midnight, so setting the unit to switch off at 3 am cools you through the worst of the night for half the cost.

*At full power on the Ofgem cap rate of 26.32p/kWh (Oct to Dec 2026). Real-world averages run 20 to 40% lower once the compressor starts cycling.

Almost every portable AC sold in the UK is single-hose, including everything on this list, and it matters more than any spec on the box.

A single-hose unit pulls in room air, runs it over the hot condenser coils, and blows it out of the window. That creates negative pressure in the room: the air it exhausts has to be replaced from somewhere, so warm air gets pulled back in through every gap around doors and windows. The unit is cooling with one hand and importing heat with the other.

The US Department of Energy created the SACC rating to measure this honestly, and the result is that real-world output from a single-hose unit is typically 25 to 50% below the marketed BTU figure. A "9,000 BTU" portable might deliver 5,000 to 7,000 BTU of net cooling. Dual-hose units avoid the problem with a separate intake hose, but they are rare in the UK, pricier and bulkier, and for 20 to 40 days of use a year the premium rarely pays back.

This is why our sizing advice says buy one step up, and it is already baked into the "realistic room size" column in our comparison table, which is deliberately more conservative than the manufacturers' claims.

Every portable AC must vent hot air outside through its hose, and here is the catch: most included window kits are designed for sash windows, while most UK homes have casement windows that swing outward on a hinge.

• Sash or sliding windows: easy. Slide the window up, fit the rigid panel from the box, feed the hose through. The included kit usually works fine.
• Casement windows (the most common UK type): the rigid panel will not fit the irregular opening. You need a fabric zip-seal kit, a sheet that attaches around the frame with adhesive Velcro and zips around the hose. They cost £15 to £30 and are vastly better than an open window, which defeats the whole exercise.
• Tilt-and-turn: use a fabric kit in the tilt position. It is the most versatile option.

Three tips that make a real difference: keep the hose as short and straight as possible, because the hose itself radiates heat back into the room; never vent into another room, which just relocates the heat; and a £5 wrap of reflective foil insulation around the hose noticeably improves performance.

Every listing quotes a decibel figure and none of them tell you what it means. Here is the translation:

For context, the British Standard BS 8233 recommends no more than 30 dB in bedrooms at night, which every portable AC on the market exceeds. Most people adapt to a steady hum within a few nights; it is the compressor clicking on and off that disturbs sleep more than the level itself.

If you are sleeping next to one: use sleep mode, stand the unit on carpet or a rubber mat to cut vibration, keep it as far from the bed as the hose allows, and set the timer to switch off around 3 am when outdoor temperatures have already fallen.

Portable AC prices in the UK follow a brutally predictable cycle, and our live price feed catches it in the act. As we write this in October, most of the units on this list are out of stock new, and the one still available is listed well above the price it sold for in June. That is the pattern, not bad luck:

• March to April: lowest prices, full stock. The right time to buy.
• May: prices start creeping as the first warm spell hits.
• June to July: prices jump and popular models sell out. Marketplace sellers routinely raise prices mid-heatwave.
• August: stock is patchy; you buy whatever is left, not what you wanted.
• September to February: listings go out of stock or carry inflated prices from third-party sellers while demand is low.

The takeaway writes itself: if you are reading this out of season, set a reminder for March and buy the unit you actually want at the year's best price. If you are reading this mid-heatwave and everything is sold out, now you know why.

A portable AC is one of the only cooling options that needs zero landlord permission: it is a freestanding appliance with a hose out of the window, not a modification to the property. Four things renters should know:

• Fabric zip-seal window kits attach with adhesive Velcro that peels off cleanly. No holes, no damage, no deposit argument.
• Never run one from an extension lead. These units draw 3 to 5 amps continuously, which can overheat a cheap lead. Wall socket only.
• Shared walls? Stay at or under 55 dB, which on this list means the Pro Breeze units or the De'Longhi. Your neighbours can hear a 65 dB unit through a party wall.
• Landlords have no obligation to provide cooling, so this purchase is on you, and it moves house with you when you go. Check your tenancy agreement for appliance clauses, though they are rare.

• "Leave the door open to circulate the cool air." No. Seal the room. An open door feeds the negative-pressure problem and lets warm air flood straight back in.
• "Bigger BTU is always better." No. Oversized units short-cycle and leave the room cold but clammy. Match the unit to the room.
• "One unit can cool the whole flat." One unit cools one sealed room. Moving it means a 20 to 30 minute wait while each new room cools from scratch.
• "The marketed BTU is what you get." Single-hose portables deliver 25 to 50% less than the headline figure, per the US Department of Energy's SACC testing. Every brand plays this game, so compare like for like and size up.
• "The hose does not matter." It radiates heat back into the room the whole time the unit runs. Short, straight, and ideally insulated.