A portable air conditioner puts the whole machine in the room with you, compressor included. That is why finding the quietest portable air conditioner matters more than it does for any other kind of AC, and why the numbers on the box deserve a careful reading. Most of them describe a setting you will not be using on a hot afternoon.
We read the product pages, spec sheets and manuals for nine portables, and for three window units as a comparison. Eight of the nine portables carry a published noise figure. Only one maker publishes a figure for every fan speed. None states the distance the sound was measured from. Here is what each one says, and what to buy for a small room.
Our 7 picks are listed above, with full specifications for each.
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. Honeywell lists 56 dBA as both the minimum and the maximum of a three-speed unit.
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.
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.
When a maker contradicts itself
We found several 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.
Portable or window: the honest comparison
If your window can take a window unit, the makers' own figures say it will be quieter.
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.
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. 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 none of those applies, see the window units under What We Also Considered, below.
The small-room problem
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.
Does oversizing matter? 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.
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.
Setting up a portable AC to run quietly
Level floor first. Midea's manual says to install the unit on an even surface to minimize noise and vibration, and lists a floor that is not level as a cause of noise. 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.
Mistakes buyers make
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.
Shopping by the big BTU number. 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.
How we chose
We read the manufacturer's product page and specification table for each unit, and the spec sheet or owner's manual where one is published. We recorded each noise figure in the maker's own words, with the fan speed it describes whenever the maker says. We compared cooling capacity under the DOE test, hose design, compressor type, the maker's room size and warranty. We checked the federal test procedure and ENERGY STAR's room air conditioner pages for anything on noise and sizing.
We did not measure decibels ourselves. We ranked a full table of figures above a single "as low as" claim, and we quoted both figures wherever a maker's page disagrees with itself. Prices shown on the cards are the makers' own list prices on the day we checked.
