How loud is a portable air conditioner?
Portable air conditioner noise figures depend on the maker: LG lists 44 to 53 dBA across four speeds, while others print one figure or none. There is no federal noise test for portable air conditioners. The Department of Energy's test procedure for portables measures cooling capacity and energy use. We searched its full text, and the words noise, sound and decibel do not appear. Every figure in this guide is therefore the maker's own number, taken its own way.
The makers fall into three groups.
A figure for every speed.
LG lists 53, 50, 47 and 44 dBA for high, medium, low and sleep. Whynter gives low, medium and high for both of its models here. Frigidaire and Danby give low and high.
One "as low as" figure.
Midea says as low as 42 dBA and nothing more. Dreo says 42 dBA and footnotes it: tested by its own lab at the lowest speed setting.
Nothing useful.
BLACK+DECKER publishes no figure. For a three-speed unit, Honeywell lists the same 56 dBA as its minimum and its maximum.
The lesson is simple. An "as low as" figure is the lowest fan speed, and you cannot rank it against another unit's full table.
At high speed, the only published portable figures we found are 53 for LG and Frigidaire, 54 for Danby, 56 and 56.5 for the two Whynters, and 56 for Honeywell.
Our decibel chart places LG's 44 dBA in sleep and 53 on high beside reference sounds from the NIDCD and the National Park Service, with a note on why that is only a rough guide.
Read the units as written, too. LG and Frigidaire say dBA. Whynter heads its row dBA and fills it with dB. Danby writes "dBs". We report each as the maker wrote it and do not treat them as the same.
Not always: we found several air conditioner pages that disagree with themselves, and we think you should know.
Whynter's ARC-1230WN is listed at under 42.5 dB on low in its specification table. The description on the same page says as low as 48 dBA.
Frigidaire's window unit is 41 dBA in the marketing copy and 40 dBA in the spec table. Midea's Duo has a one-year warranty on the product page and two years in the manual. LG's spec sheet says 500 square feet, and its current product page says 450.
None of this is scandalous. It does show that these figures are written by marketing departments, not by a test lab with a standard to follow. Treat a difference of one or two decibels between brands as no difference at all.
Is a portable AC louder than a window unit?
Usually: if your window can take a window unit, the makers' own figures say it will be quieter than a portable AC.
Frigidaire makes the cleanest comparison, because it publishes both in the same format. Its small portable is 50 dBA on low and 53 on high. Its inverter window unit is 40 on low, 46 on medium and 50 on high. The window unit at full speed is as quiet as the portable at its lowest. Our window air conditioner guide ranks the window units in full.
Midea tells the same story with less detail: as low as 42 dBA for the Duo portable, as low as 32 dBA for its U-shaped window unit. Our list of Midea's published air conditioner figures shows that all four Duo portables carry the same 42 dBA line. ENERGY STAR explains why that design helps. On U-shaped and saddle units, it says, the noise-producing compressor is located outside the room.
LG is the exception. It lists 44 in sleep mode for both its inverter portable and its inverter window unit.
So buy a portable when you have to: a sliding or casement window, a lease that bans window units, or a room you cool only now and then.
If your building has a wall sleeve, our through-the-wall guide covers the units that slide into it. A wider sleeve, about 42 inches across, usually holds a PTAC, and our PTAC guide covers those 208/230V units. If none of those applies, see the window units under What We Also Considered, below.
In a dry climate there is one more option. Our guide to the quietest evaporative air coolers covers swamp coolers, which cool the air by evaporating water from a wet pad, and says plainly that they are no substitute where summers are humid: Honeywell says its coolers work best below 60% relative humidity.
What is the quietest portable air conditioner for a small room?
The quietest portable air conditioner for a small room is a choice between a right-sized Frigidaire or Danby and an oversized LG that is quieter on paper. The quietest portables are all big. The LG, the Midea and the Dreo are each rated at 10,000 BTU by the DOE test and sold for rooms of 400 square feet or more.
ENERGY STAR's sizing table for room air conditioners suggests 5,000 BTU for 100 to 150 square feet, and 6,000 for up to 250.
Those big units fit a living room better, and our guide to the quietest portable AC for a living room ranks the living room sizes by their medium and high figures, the speeds they run at in the evening.
Oversizing has its own cost. ENERGY STAR warns that a unit that is too large will cool the room before it has had a chance to remove the humidity, which leaves the air damp and clammy.
That advice was written for ordinary room units. An inverter compressor can slow down where an ordinary one can only switch off, and ENERGY STAR says variable output lets an air conditioner cool a room quietly.
No maker we read says how its inverter portable behaves in a room a third of its rated size, so we will not promise that it solves the problem.
That leaves a real choice for a small room:
- Right-sized and cheaper: the Frigidaire at 50 to 53 dBA, or the Danby at 51 to 54. Both are single-hose units without inverters, and both are rated for 150 square feet.
- Oversized and quieter on paper: the LG, at 44 to 53 dBA, for about twice the price.
Can you run a portable AC all night in a bedroom?
Yes, and on the makers' documents the LG is our bedroom choice. Next to a bed, three questions matter more than the figure on the box, and the owner's manuals answer them where the spec tables say nothing: what the sleep button changes, what happens when the condensate tray fills, and whether the display goes dark.
LG alone gives its sleep setting a figure, 44 dBA for Sleep on its spec sheet. Its manual says Sleep Mode "keeps operating noise to a minimum and turns the air conditioner off after a set time", from 1 to 12 hours, and switches the control panel off, so pick a timer long enough to last the night.
On the Frigidaire, sleep sets the fan "as Auto automatically, which cannot be changed", and Frigidaire prints no figure for Auto; Cool with the fan on low is the setting that has one, 50 dBA.
The Midea Duo's sleep button raises the set temperature by 2 degrees F at 30 minutes and again at 60, and Danby's, which works only from the remote, raises it 1 degree an hour for 2 hours. Neither manual describes any change to the fan. Dreo lists Sleep among the 740S modes without saying what it does.
The full tray
Each unit stops cooling once its tray fills. The Midea Duo "beeps 8 times", shows P1 and stops cooling while its fan runs on. The LG shows FL and turns itself off, and its manual mentions no alarm.
Dreo calls the 740S drainage-free "in Environments Below 90% Humidity", and Whynter says the ARC-1280MX's auto drain "fully exhausts all condensate automatically in most environments", so on their makers' word a tray stop should be rare on those two.
The Midea Duo's remote has an LED button that turns the display off, and on some models the buzzer too. Holding the LG's Mode button for 3 seconds steps its panel from full brightness to half and then off. The Frigidaire and Danby manuals give no way to darken the display.
On those documents the LG stays our bedroom choice, with the Dreo worth a look where summer nights are humid. One LG setting to check before bed: an optional condensation fan, off by default, keeps the fan running for 10 minutes after you switch the unit off and shows Co.
How much should you spend?
Around $330 to $350 buys a small single-hose unit with both fan speeds published. Expect a CEER near 6, which means higher running costs.
Around $470 to $500 buys a dual-hose inverter: the Whynter ARC-1280MX with a full speed table, or the Midea Duo with the best efficiency and a single noise figure.
Around $700 buys the LG or the Dreo. At that price we would take the LG, because it publishes four figures where Dreo publishes one.
Efficiency is worth a look at any price. The CEER figures here run from about 6 for the small single-hose units to 14.7 for the Midea Duo. If you run the unit all summer, that gap shows up on the electricity bill.
How do you make a portable AC quieter?
Set it level, keep the hose short, give it space, clean the filter, run the lowest comfortable fan speed and plug it into the wall.
Level floor first. Midea's manual says to install the unit on an even surface to minimize noise and vibration, and blames noise partly on a floor that slopes. Danby's manual lists the same cause.
Keep the hose short and straight. Frigidaire says to keep the exhaust hose to the minimum length required, with no sharp bends or sags. Midea says not to add an extension at all.
Give it room. Midea asks for at least 9.8 inches from the nearest wall. Danby asks for 17.7 inches at the front and sides and 20 inches behind.
Clean the filter. A blocked filter is on both Midea's and Danby's list of noise causes. Frigidaire's filter light comes on after 250 hours of fan use.
Use the lowest fan speed that keeps you comfortable. Frigidaire's own advice for a unit that is too loud is to set a lower fan setting. Every published table in this guide shows a gap of 3 to 14 decibels between low and high.
Plug it into the wall. Midea, Frigidaire and Danby all say not to use an extension cord.
What do buyers get wrong about portable AC noise ratings?
Five portable AC buying mistakes stand out in the makers' documents, from comparing unlike figures to stretching the hose.
Comparing an "as low as" number with a full table
The Midea's 42 and the LG's 53 describe different fan speeds. The LG's own low-speed figures are 47 and 44.
The ASHRAE figure on the box is always larger than the DOE figure. Size the unit by the DOE number.
Assuming dual hose means quiet
No maker claims it. The quiet units are inverter models that also happen to have two hoses.
Trusting everyday comparisons
You will read that 42 decibels is as quiet as a library. No maker or standards body we read supports comparisons like that, so we leave them out.
Extending the hose to reach a far window
The makers advise against it.
Midea's 42 dBA and Dreo's 42 dBA look identical, but only Dreo says its figure is its own lab's reading at the lowest speed, the kind of difference our page on comparing decibel ratings explains.
Whether your small room is a bedroom or an office changes what to aim for, and our page on how quiet is quiet enough takes both.
If a portable you already own has grown louder even on a level floor with a clean filter, our page on why your appliance got louder has more checks from the makers' manuals.
