A through-the-wall air conditioner lives in a metal sleeve in an exterior wall, which makes it the default in a lot of apartments and condos, and often the only option where the building or the local rules do not allow a unit hanging in a window. If that is your situation, our guide to keeping an apartment quiet explains what your neighbors hear through the wall; this guide covers what the unit itself will do.
The bad news first: this category is documented far worse than window units. We read the product pages, spec sheets, brochures and manuals for through-the-wall units from six brands. Only three of them, Frigidaire, LG and Keystone, publish decibel figures at all. The other three, GE, Midea and Friedrich, publish none that we could find. Here is what the twelve documented units say, and which one to put in your wall.
Our picks are listed above, with full specifications for each.
What the makers that publish actually publish
Frigidaire names every speed. Its product specifications sheets carry three rows: Noise Level dBA (Low), (Med) and (High). The newest 8,000 BTU wall unit, the FHTC083WB1, lists 49.5, 52.5 and 56 dBA. The 8,300 BTU FHTC083WA1, the heat-capable FHTE083WA1 and the built-in FFTA083WA1 all list 52, 54 and 57. The 12,000 BTU FHTC123WA1 lists 57, 59 and 60.
LG publishes two kinds of figures. Its 8,000 and 9,800 BTU wall units get a per-speed row, "dBA Level (High/Mid/Low)", both reading 56/55/53, and every LG wall unit also gets a pair labeled "dBA Level (Indoor / Outdoor)": 56/62 for the LT0816CER, 56/65 for the LT1016CER, 60/66 for the LT1216CER, 56/63 and 59/65 for the two heat and cool models. LG does not say which fan speed the indoor/outdoor pair describes.
Keystone publishes pairs without labels. Its through-the-wall spec sheet lists an "Indoor Noise Level dBA" line per model, most with two values: 56.8 / 51.8 for the 8,000 BTU KSTAT08-1D, 60.5 / 56.5 for the 12,000 BTU models. The sheet never says which speed each value belongs to, though the KSTAT08-1D product page calls the 51.8 figure "on low".
We print each figure exactly as the maker wrote it, and we do not rank a per-speed figure against an unlabeled one. None of these makers states a measuring distance or a test standard, so treat differences of a decibel or two across brands as noise in the data, and trust comparisons within one brand most.
Three big brands publish nothing
GE Appliances sells a full built-in wall lineup. We read the AJCQ08AWJ product page, its quick specs sheet, GE's built-in and universal fit wall air conditioners brochure, the dimensions and installation guide and the owner's manual, and none of them carries a decibel figure. The manual discusses noise only to say that air movement sound is normal and to suggest a slower fan setting.
Midea sells in-wall units from 8,000 to 14,000 BTU. Its product pages for the MAT08R1ZWT and MAT12R1ZWT state no noise figure anywhere, and both pages were marked "This product is no longer available" when we checked, which suggests the lineup is being wound down.
Friedrich is the strangest case, because quiet is its whole pitch. Its Uni-Fit and WallMaster through-the-wall lines are built around QuietMaster technology, described across a solid steel inner wall, high density insulation, and counterweights for vibration dampening, with a claim of "up to 25% quieter" that is footnoted to internal testing against "leading rotary compressor models". We read the 2026 brochures and the engineering submittals for both lines: cooling capacity, amps, CFM and sleeve dimensions are all there, and not one decibel figure. A claim without a number is not something we can rank, so Friedrich sits outside this list despite arguably being the category's premium name.
No inverters here, and what that costs you
Every compressor in this guide is a plain rotary unit that cycles on and off. Not one maker describes a through-the-wall model as an inverter, in a year when inverter window units dominate our window guide.
Frigidaire's own sheets show what that costs. Its quietest wall unit lists 49.5 dBA on low. Its inverter window unit, the Gallery GHWW085TE1, lists 40 dBA on low and 50 on high, so the window inverter's loudest published speed roughly matches the wall unit's quietest. Against Frigidaire's conventional window unit at 53.5 to 59 dBA, though, the wall units hold up well: sleeve mounting puts the compressor in the wall rather than on the sill, and the newest wall unit's whole range sits below the conventional window unit's.
The practical read: if your building allows window units and quiet is the priority, an inverter window model is the better tool. If the wall sleeve is what you have, the FHTC083WB1's numbers are the best on paper, and nothing about the category should embarrass it at low speed.
Sleeves, trim kits and fit
A wall unit is a chassis that slides into a sleeve, and the sleeve does more for noise than it gets credit for: it carries the unit's weight, and a loose fit leaves gaps that leak sound and air around the chassis.
Every unit here ships without a sleeve. Frigidaire's wall models want a 26 inch wide sleeve (part 912001373) and tolerate walls up to 18 inches thick. Keystone sells the KSTSLV1, 25.5 inches wide. LG includes a trim kit and rear grille and sells its sleeve separately. If you are replacing an old unit, measure the sleeve you have before you shop: Friedrich's submittal prints a whole table of competitor sleeve dimensions, from 24 1/2 to 27 inches wide, precisely because most wall unit purchases are replacements into someone else's old sleeve.
One quiet difference worth noticing: the Frigidaire FFTA083WA1 discharges air from the top with a swing louver, while the FHTC wall models discharge from the front. Same published figures, different sleeve width, so check which your opening matches.
Check the outlet before you order
The 8,000 BTU class and Frigidaire's 12,000 BTU unit run on a standard 115V outlet. LG's two heat and cool models need 208/230V, and Keystone says its 12,000 BTU KSTAT12-2D requires a special 230-volt/20-amp outlet and will not operate on a standard one. Many older buildings put a 230V receptacle behind the sleeve for exactly these units; many did not. This is the first thing to check, before price and before decibels, because it cuts the candidate list in half.
Size it for the room
Friedrich's cooling sizing guide, one of the genuinely useful things in its literature, puts 300 to 350 sq ft at 8,000 BTU, 400 to 450 at 10,000 and 450 to 550 at 12,000, with adjustments of 10 percent either way for shade or strong sun, 500 BTU per person beyond two, and 4,000 BTU for a kitchen.
The noise sheets give you a second reason not to oversize. Frigidaire's 12,000 BTU unit starts at 57 dBA on low, as loud as its 8,000 BTU units ever get. Keystone's 12,000 BTU models list 60.5 dBA where its 8,000 BTU unit lists 56.8. Within each brand, the smaller unit is the quieter unit at every published point.
What you will pay
Keystone is the value play: $549.99 for the KSTAT08-1D and $649.99 for the 230V 12,000 BTU unit on its own site. LG lists $579 for the 8,000 BTU LT0816CER, $629 and $599 for the bigger cool-only units, and $729 to $799 for the heat and cool pair, but every LG wall unit's page carried out-of-stock product data when we checked in late September, at the end of cooling season. Frigidaire's site refused our requests entirely on the day we checked, so we recorded its specifications from its published spec sheets and no prices. Wall units run $150 to $250 more than window units of the same size, and the sleeve, if you need a new one, is another cost on top.
Mistakes buyers make
Comparing a labeled figure with an unlabeled one. Keystone's 51.8 and Frigidaire's 49.5 look close, but only Frigidaire's sheet tells you the speed for every figure it prints.
Assuming the premium brand has the numbers. Friedrich charges the most and publishes the least for its wall units: no decibel figure at all, just a percentage claim against unnamed rivals.
Ignoring the outdoor side. Only LG tells you what leaves the back of the unit, up to 66 dBA. If the wall faces a neighbor's bedroom or a courtyard, that number matters as much as the indoor one.
Buying capacity you do not need. Every brand's own sheets show the 12,000 BTU class starting louder than the 8,000 BTU class ends.
New to decibel specs? Start with dBA explained, and see why you cannot compare dB ratings across brands before you weigh a Keystone figure against an LG one. For what to aim for in a bedroom, see how quiet is quiet enough.
How we chose
We read the manufacturer's specifications sheet for every Frigidaire and Keystone unit, LG's product page spec tables and spec sheet, and the brochures, submittals and manuals for the brands that publish no figures. We recorded every noise figure verbatim with its label, and we ranked only like against like: per-speed figures against per-speed figures, within their stated speeds. We compared capacity, voltage, sleeve fit, heat options and the maker's room sizing, and we recorded prices only from the makers' own sites on the day we checked.
We did not measure decibels ourselves. Every figure in this guide is the maker's own claim, printed in the maker's own words, and where a maker publishes nothing we said so rather than guessing.
