What size window AC do you need for a bedroom?
Smaller than most window units are sold as. Assuming an 8-foot ceiling, ENERGY STAR matches floor area to capacity like this:
| Bedroom floor area | Capacity |
|---|
| 100 to 150 sq ft | 5,000 BTU |
| 150 to 250 sq ft | 6,000 BTU |
| 250 to 300 sq ft | 7,000 BTU |
| 300 to 350 sq ft | 8,000 BTU |
| 350 to 400 sq ft | 9,000 BTU |
| 400 to 450 sq ft | 10,000 BTU |
A 12 by 12 foot room is 144 sq ft, the 5,000 BTU band. A 12 by 14 foot room is 168 sq ft, the 6,000 BTU band. Only a fairly large bedroom, 300 sq ft or more, needs the 8,000 BTU unit that most "quiet" models are sold as. Shade and sun shift the bands: ENERGY STAR takes 10 percent off for a heavily shaded bedroom and adds 10 percent for a very sunny one.
Oversizing costs you twice at night.
First, an oversized unit, ENERGY STAR warns, will cool the room before it has a chance to remove the humidity, leaving cool, moist air that feels damp and clammy. Second, the bigger units list higher figures. LG's 10,000 BTU inverter lists 58, 54 and 50 dBA from high to low, while its 8,000 BTU inverter lists 54, 50 and 46, which is 4 dBA more at every fan speed for capacity a small bedroom does not need.
So the picks are grouped by room size. The Frigidaire Gallery, LG LW8022IVSM and Midea U are 8,000 BTU units that their makers rate for up to 350 sq ft. The GE Profile PHNT10CC is 10,300 BTU for 350 to 450 sq ft, and the LG LW6023IVSM is 6,000 BTU for up to 250 sq ft by its features text, though its spec table says up to 300.
Frigidaire puts the Gallery at 40 dBA on low, 50 on high. LG puts the LW8022IVSM at 46 on low. No other 8,000 BTU standard unit here prints a low-fan number under the Gallery's.
Makers quote their quietest setting. In a bedroom that is not a trick, because the quietest setting is the one you will use. The trouble is that each maker's quietest setting is a different thing.
LG is alone here in putting its sleep setting in the spec table, at 44 dBA for both the 8,000 and 10,000 BTU inverters; on the 8,000 BTU model that sits 2 dBA under the low-fan figure from the same table.
The PHNT10CC's 40 dBA belongs to Quiet Mode, labelled "Low Cool", which the manual says sets the fan to Low. In ordinary Cool, GE lists low fan at 51. The manual adds that in Quiet Mode the unit runs for longer at lower energy consumption levels, which is the likely reason for the gap, though GE does not say so.
Midea's as low as 32 dBA and LG's as low as 44 dB for the 6,000 BTU unit come with no setting at all. Midea prints that same line for all ten of its U-shaped units, as our page of every Midea air conditioner's figure shows, so within the U range the number cannot separate the models.
None of these is ranked against the others. A low-fan figure, a sleep figure and a Quiet Mode figure describe different settings, and no maker states a distance or a test standard. Compare within one maker's sheet, where the conditions are at least the same.
What does sleep mode do on a window air conditioner?
Something different on each brand, and the manuals are clear about it.
Frigidaire Gallery
Sleep can only be switched on by remote or app. The display shows SL for 3 seconds, then the display and lights turn off. The unit "will automatically select the Auto fan speed", nudges the set point up 2 degrees F after 30 minutes and 2 more after another 30, and holds that for 7 hours. On Auto, the fan starts on High and speeds up again if the room warms.
For the quietest night, use Cool on Low fan and let the display dim by itself.
LG LW8022IVSM and LW6023IVSM
Sleep Mode "keeps operating noise to a minimum and turns the air conditioner off after a set time", which you pick between 1 and 12 hours, while letting the set temperature climb by up to 4 degrees F. Set the timer long enough to reach morning.
Midea U
After 30 minutes in Sleep, the set temperature goes up 2 degrees F and stays there for 7 hours. The manual says nothing about the fan speed in sleep.
GE Profile PHNT10CC
There is no sleep mode in its manual. For quieter nighttime cooling, GE says to use Cool with Low fan, and it offers Quiet Mode, with a warning that in Quiet Mode it is normal to hear the unit switching speeds when it senses the room becoming uncomfortable.
Is an inverter window AC quieter at night?
On the steady figures, clearly. Frigidaire's conventional FHWC083TC1 lists 53.5 dBA on low, 13.5 above the Gallery inverter's 40. An inverter does not end the compressor cycling you notice at night, though.
In the daytime you hear the steady noise. At night you notice changes: the compressor starting, the fan ramping up, a click. ENERGY STAR describes a conventional compressor as working "like an on/off switch", on at maximum capacity or off, alternating to hold the temperature, while a variable speed compressor varies its speed to continuously control the temperature. GE's manual for its non-inverter ClearView units says you may hear the thermostat click when the compressor cycles on and off.
Inverters still cycle. GE's inverter manual says the compressor "will cycle on and off and also change operating speeds", and Frigidaire's says an inverter model may make a "da-da" sound within the first thirty seconds as the compressor starts.
Why does a window AC fan keep turning on and off?
Usually an energy saving mode. At the set temperature it turns the fan off, then restarts it to sample the room, and it is on by default on four of the five picks. This was the bedroom problem we did not expect.
| Unit | Mode and default | What the fan does |
|---|
| LG | Energy Saver, on every time the unit is switched on | At the set temperature, both compressor and fan shut off; the fan turns on approximately every 3 minutes to sample the room |
| Midea U | Energy Saver, on by default | Fan runs 3 minutes after the compressor stops, then cycles on for 2 minutes at 10 minute intervals |
| Frigidaire Gallery | Eco, on at first use and back on when restarted in Cool | Same pattern, 2 minutes every 10 |
| GE PHNT10CC | Eco | Fan cycles with the compressor and may pulse intermittently to sample the room air |
At night, a fan that stops dead and then spins up again is easier to notice than one running steadily at low speed. If the restarts wake you, switch the mode off at bedtime and use a low fan.
Display lights and beeps can be turned off
All four brands let the display go dark, either by itself or with a button, and GE and some Midea models also silence the beeps. Nobody minds them in a kitchen; beside a pillow, in a dark and quiet room, they are a problem.
| Unit | Display | Beeps |
|---|
| Frigidaire Gallery | Display and indicator lights switch off after 60 seconds with no input | Beeps twice when you hold the temperature button to its upper or lower limit |
| LG | Light Off function: hold Mode on the remote for 3 seconds, or press Mode and Sleep together on the unit | None noted |
| Midea U | LED button on the remote switches the display on and off | The same button mutes the buzzer on some models; the unit beeps when it receives a remote signal |
| GE PHNT10CC | Panel lights turn off after a minute without use | On by default; hold Filter for 5 seconds to silence them |
U-shaped and saddle units move the compressor outside
ENERGY STAR credits these designs with greater noise reduction, though it gives no figure.
A U-shaped unit like the Midea straddles the sash, and a saddle unit like the GE hangs over the sill. In most such designs the controls and vent stay on the bedroom side, and ENERGY STAR notes that "the noise-producing compressor is located outside the room". Soleus Air's saddle unit is the only one we found with separate figures: 38 to 49 dB(A) indoors and 51 to 63 outdoors.
Two more points for a bedroom. Both designs let you open the window with the unit installed, which helps if you like air on cool nights. Both are heavy: the GE PHNT10CC weighs 80 pounds and needs a wall and window of the right size. For the window, sash and wall sizes these designs require, see our U-shaped and saddle window unit guide, which picks the Frigidaire Gallery GHWQ085WD1 for a bedroom up to 350 sq ft.
If you can make a permanent change, a mini-split moves the compressor out of the room entirely. For each indoor head, our mini-split sizing notes for bedrooms give the figure at its slowest fan speed.
Normal night sounds, and the one you can fix
The manuals list the same ones: rushing air, a gurgle or hiss from the refrigerant, a high pitched chatter from the compressor, and pinging as water is thrown against the condenser. A bedroom at night has little background noise to cover them.
Vibration is the one you can fix. LG tells you to mount the unit securely and firmly so it does not vibrate and make noise, and Midea's manual blames vibration on poor wall or window construction or incorrect installation.
The target for a sleeping room is set in how quiet a bedroom should be. An LG sleep figure and a Frigidaire low-fan figure do not line up, and comparing dB ratings across brands explains the reasons.
