Quietest air conditioners UK: quiet units compared by real dB figures

The quietest air conditioners for a UK home are wall-mounted split systems. Their indoor units run at 16 to 19 dB(A) on the lowest fan setting, quieter than a whisper and well below the World Health Organization's guidance of 30 dB(A) in a bedroom at night. Of the splits we review, the Samsung WindFree Elite is the quietest at 16 dB(A), followed by the Mitsubishi Electric MSZ-AY at 18 dB(A), with most premium Daikin, Mitsubishi Electric, Panasonic, Toshiba, and LG models at 19 dB(A).

Splits are quiet because the noisy part, the compressor, sits in the outdoor unit. Put the compressor in the room, as a portable does, and the noise jumps: even "Silent" one-piece portables bottom out at about 44 to 50 dB(A), around the level of a quiet office. No air conditioner is truly silent, but a fitted split on its quiet setting is as close as you'll get.

The quietest air conditioners by type

Every type of air conditioner can be quiet or loud depending on the model, but the order below holds. Figures are the quietest published indoor sound pressure on the lowest setting.

Manufacturer figures, best case, measured on the lowest fan at a set distance. Real rooms and higher fan speeds are louder. Checked November 2026.

If you can have a split fitted, that's the quiet option. If you can't, our guide to the quietest portable air conditioners ranks every portable we review by noise.

The quietest split air conditioners we review

These are the wall-mounted splits we've reviewed, ranked by their quietest indoor figure. The low figures apply to the small and medium sizes; bigger units are louder.

The differences between 16 and 20 dB(A) are small next to the 25 dB(A) or more that separates any of these from a portable. Choose between these on size, efficiency, looks, and price, then let quiet mode do the rest. Our round-up of the best wall-mounted air conditioners picks between them by job.

How quiet is quiet enough?

For sleep, the number to know is 30 dB(A). The WHO recommends keeping bedroom noise below that at night. It's health guidance rather than an appliance standard, but it's the right yardstick, and every split in the table above sits well under it on its quiet setting.

Decibels are logarithmic, so a 10 dB rise sounds roughly twice as loud. That makes the gap between a split at 19 dB(A) and a portable at 49 dB(A) much bigger than the numbers suggest: the portable sounds about eight times as loud.

Sound power vs sound pressure: the number that misleads

Two different numbers get quoted as "dB", and mixing them up is the most common way air conditioner noise claims mislead.

• Sound pressure is what you hear at a given spot, usually 1 m from the unit in test conditions. It changes with distance and the room. This is the figure in our tables.

• Sound power is the total sound energy the unit gives off, wherever you stand. It's always the bigger number, typically 10 to 13 dB(A) higher for a small outdoor unit, and it's the figure on the energy label.

The same unit can carry both. Mitsubishi Electric quotes the MSZ-AY at 18 dB(A) sound pressure, while one retailer lists the 2.5 kW system at "57 dB sound power". De'Longhi quotes its Pinguino PAC EM82 portable at 47 to 50 dB(A), while its energy label shows 63 dB(A) of sound power. Neither number is wrong; they measure different things. Compare sound pressure with sound pressure, and be wary of any listing that gives a single unlabelled "dB" figure.

Don't forget the outdoor unit

A split moves the noise outside rather than making it disappear. A typical 2.5 to 3.5 kW outdoor unit is about 45 to 50 dB(A) at 1 m (sound pressure), roughly a quiet office if you stand next to it, and it's slightly louder in heating mode than in cooling.

That matters for the neighbours. In England, a reverse-cycle unit on a house can go in under permitted development only if it passes the MCS 020 a) calculation: 37 dB(A) or less at 1 m from a neighbour's habitable-room window. Placement does most of the work, so a good installer will check the siting before quoting. Our guide to heat pump noise and the 37 dB(A) rule explains the test, and our planning permission guide covers the other conditions.

Air conditioners without an outdoor unit aren't silent outside either. A monobloc such as the Unico EVO vents through two grilles in the external wall, and makers publish only the indoor figure. Indoors, the compressor sits inside the unit, so expect a low hum even when the decibel figure looks modest. Our guide to air conditioning without an outdoor unit covers the trade-offs.

Is there such a thing as a silent air conditioner?

No. Every air conditioner moves air with a fan and pumps refrigerant with a compressor, and both make some noise. "Silent" on a product name usually means a quiet mode, not silence: De'Longhi's Pinguino PAC EX100 Silent starts at about 49 dB(A).

The closest thing to silent is a wall-mounted split on its quiet or night setting, at 16 to 19 dB(A). That's near the threshold most people notice in a quiet bedroom. Be wary of £30 to £40 "silent mini air conditioners": they're evaporative coolers, a fan blowing over a wet pad, and they barely cool a room in a humid UK summer.

The quietest portable air conditioners

If you can't install a split, the quietest portable we review is the Midea PortaSplit, at 39 dB(A) indoors, because its compressor sits in a separate box outside the window. Among one-piece portables, the Meaco Cirro 12000 drops to about 45 dB in its Super Quiet mode and the De'Longhi Pinguino PAC EX100 Silent starts at about 49 dB(A).

All of these are well above 30 dB(A), so a portable in a bedroom is always a compromise. Our guide to the quietest portable air conditioners ranks them all, with prices and stock.

How to keep any air conditioner quiet

Get the size right. A unit that's too small runs flat out and gets loud. One that's too big is noisier at its quietest: Panasonic's Etherea runs at 19 dB(A) on the 3.5 kW but 30 dB(A) on the 5.0 kW. Use our BTU calculator or sizing guide before you buy.

Use quiet and night modes. They slow the fan and compressor and ease the set temperature overnight. They won't make a portable quiet, but on a split they're how you get to the 16 to 19 dB(A) figures.

Pre-cool the room. Run the unit harder in the evening, then let it tick over on quiet mode once you're in bed.

Have it fitted properly. A level bracket, isolation feet on the outdoor unit, and a sensible spot away from bedroom windows (yours and the neighbours') all cut noise and vibration.

Keep it clean. Clogged filters make the fan work harder and louder. Our maintenance guide shows you how.

For bedrooms in particular, our bedroom air conditioning guide covers sizing, sleep modes, and running costs.