8,000 BTU is the most common portable air conditioner rating and a popular window size. As a window unit in an average room it cools up to about 400 sq ft, with a best fit of 300 to 400 sq ft. The Energy Star chart puts it at 300 to 350 sq ft, the same answer with a little more margin.
Portables need a caveat. Portable ACs carry two ratings: the older ASHRAE number and the lower SACC number, which accounts for the hot outside air a single-hose unit pulls into the room. An 8,000 BTU ASHRAE portable is often about 5,000 BTU SACC, which cools about 250 sq ft, not 400. Size a portable by its SACC figure.
For a window unit, sun and insulation move the limit from about 310 sq ft (sunny, poorly insulated) to about 490 sq ft (shaded, well insulated). People matter too: four people need 1,200 BTU more than two, which on its own takes 60 sq ft off what the unit can cover. That is why an 8,000 BTU unit that is fine in a 350 sq ft bedroom struggles in a 350 sq ft den on game night.
As heat, 8,000 BTU warms about 200 sq ft in a moderate climate and 140 sq ft in a cold one. An 8,000 BTU window AC draws about 730 W, 6.3 A at 115 V. Converted, 8,000 BTU/hr is 2.34 kW, 2,345 W, or two thirds of a ton.
How many square feet a 8,000 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 | 490 sq ft |
| Average room (baseline) | 400 sq ft |
| Very sunny, poor insulation | 310 sq ft |
| Hot climate, very sunny | 330 sq ft |
| 10 ft ceiling | 320 sq ft |
| 4 people instead of 2 | 340 sq ft |
| Kitchen in the space | 200 sq ft |
How many square feet 8,000 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 | 220 sq ft | 260 sq ft | 310 sq ft |
| moderate | 160 sq ft | 200 sq ft | 230 sq ft |
| cold | 120 sq ft | 140 sq ft | 170 sq ft |
8,000 BTU in kW, watts and tons
| Kilowatts | 2.34 kW |
| Watts | 2,345 W |
| Tons of cooling | 0.67 tons |
| Power an AC this size draws (EER 11) | about 727 W, 6.3 A at 115 V |
| Power an electric heater needs for this output | 2,345 W, 9.8 A at 240 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.
8,000 BTU questions
How many square feet will an 8,000 BTU air conditioner cool?
About 400 sq ft in an average room for a window unit, with a best fit of 300 to 400 sq ft. A shaded, well insulated room can go to about 490 sq ft; a sunny, poorly insulated one about 310.
Will an 8,000 BTU portable AC cool 400 square feet?
Only if 8,000 is its SACC rating. If the box says 8,000 BTU ASHRAE and around 5,000 BTU SACC, expect it to cool about 250 sq ft.
What is 8,000 BTU in tons?
0.67 tons. One ton of cooling is 12,000 BTU/hr, so 8,000 ÷ 12,000 = 0.67.