5,000 BTU is the smallest window air conditioner you can buy, and it is also almost exactly what a standard 1,500 W plug-in space heater puts out (1,500 × 3.412 = 5,118 BTU/hr). So this one number answers two questions: how big a room a small window unit cools, and how big a room one space heater can warm.
At 20 BTU per square foot, a 5,000 BTU air conditioner covers up to about 250 sq ft in an average room, and about 300 sq ft if the room is shaded and well insulated. In a sunny, poorly insulated room the limit drops to about 190 sq ft. Many boxes print 100 to 150 sq ft, the conservative figure from the Energy Star sizing chart. Either way it is the right unit for a bedroom up to 12 by 15, a dorm room or a home office. Under 100 sq ft it is already oversized, so pick a model with a low fan speed or an inverter compressor rather than hunting for something smaller, because nothing smaller is sold.
As a heater, 5,000 BTU warms about 120 sq ft in a moderate climate, 160 sq ft in a hot one, and only about 90 sq ft in a cold one. That is why one space heater feels generous in a small bedroom and useless in a living room. If the room is bigger than that, the fix is a second heater on a different circuit or a 240 V unit, not a higher setting: every 1,500 W heater is capped at the same output.
A 5,000 BTU window AC draws around 450 W, about 4 A on a 115 V outlet, which is cheap enough to run all night. The same output from a resistance heater takes about 1,465 W, 12.2 A on a 120 V circuit. That is why a space heater and a hair dryer on the same circuit trip the breaker.
How many square feet a 5,000 BTU air conditioner cools
Largest room the unit keeps up with, rounded down to the nearest 10 sq ft. Two occupants, 8 ft ceiling and moderate climate unless the row says otherwise.
| Room | Cools up to |
|---|---|
| Shaded, good insulation | 300 sq ft |
| Average room (baseline) | 250 sq ft |
| Very sunny, poor insulation | 190 sq ft |
| Hot climate, very sunny | 200 sq ft |
| 10 ft ceiling | 200 sq ft |
| 4 people instead of 2 | 190 sq ft |
| Kitchen in the space | 50 sq ft |
How many square feet 5,000 BTU of heat covers
By climate and insulation. For a gas heater, use its output rating (input × efficiency).
| Climate | Poor insulation | Average insulation | Good insulation |
|---|---|---|---|
| hot | 130 sq ft | 160 sq ft | 190 sq ft |
| moderate | 100 sq ft | 120 sq ft | 140 sq ft |
| cold | 70 sq ft | 90 sq ft | 100 sq ft |
5,000 BTU in kW, watts and tons
| Kilowatts | 1.47 kW |
| Watts | 1,465 W |
| Tons of cooling | 0.42 tons |
| Power an AC this size draws (EER 11) | about 455 W, 4.0 A at 115 V |
| Power an electric heater needs for this output | 1,465 W, 12.2 A at 120 V |
kW and watts here are heat output, the number on the box. An air conditioner moves that much heat while drawing far less electricity; an electric heater draws exactly as much as it puts out.
5,000 BTU questions
How many square feet will a 5,000 BTU air conditioner cool?
About 250 sq ft in an average room with two people and an 8 ft ceiling, up to about 300 sq ft if it is shaded and well insulated, and about 190 sq ft if it is sunny and poorly insulated.
Is a 1,500 watt heater 5,000 BTU?
Close to it. 1,500 W × 3.412 = 5,118 BTU/hr. Every 1,500 W electric heater, whether oil-filled, ceramic or infrared, puts out that same amount of heat. The label differences are about how the heat is delivered, not how much.
Can a 5,000 BTU AC cool a 12 × 12 room?
Easily. A 12 × 12 room is 144 sq ft and needs about 2,900 BTU/hr in average conditions. The 5,000 BTU unit has plenty of headroom; choose one with a low fan setting so it does not short-cycle.