BTU by Room Size
Every size below has its own page with cooling tables by sun and insulation, heating tables by climate, the unit class to buy, and a pre-filled calculator. Values here are the average-room baseline: two people, 8 ft ceiling, moderate climate.
By square footage
| Room size | Cooling BTU/hr | Tons | AC to buy | Heating (moderate) | Heating (cold) |
|---|---|---|---|---|---|
| 100 sq ft | 2,000 | 0.17 | 5,000 BTU | 4,000 | 5,500 |
| 150 sq ft | 3,000 | 0.25 | 5,000 BTU | 6,000 | 8,300 |
| 200 sq ft | 4,000 | 0.33 | 5,000 BTU | 8,000 | 11,000 |
| 250 sq ft | 5,000 | 0.42 | 5,000 BTU | 10,000 | 13,800 |
| 300 sq ft | 6,000 | 0.5 | 6,000 BTU | 12,000 | 16,500 |
| 350 sq ft | 7,000 | 0.58 | 8,000 BTU | 14,000 | 19,300 |
| 400 sq ft | 8,000 | 0.67 | 8,000 BTU | 16,000 | 22,000 |
| 450 sq ft | 9,000 | 0.75 | 10,000 BTU | 18,000 | 24,800 |
| 500 sq ft | 10,000 | 0.83 | 10,000 BTU | 20,000 | 27,500 |
| 550 sq ft | 11,000 | 0.92 | 12,000 BTU | 22,000 | 30,300 |
| 600 sq ft | 12,000 | 1 | 12,000 BTU | 24,000 | 33,000 |
| 700 sq ft | 14,000 | 1.17 | 14,000 BTU | 28,000 | 38,500 |
| 800 sq ft | 16,000 | 1.33 | 18,000 BTU | 32,000 | 44,000 |
| 900 sq ft | 18,000 | 1.5 | 18,000 BTU | 36,000 | 49,500 |
| 1,000 sq ft | 20,000 | 1.67 | 24,000 BTU | 40,000 | 55,000 |
| 1,200 sq ft | 24,000 | 2 | 24,000 BTU | 48,000 | 66,000 |
| 1,400 sq ft | 28,000 | 2.33 | 30,000 BTU | 56,000 | 77,000 |
| 1,500 sq ft | 30,000 | 2.5 | 30,000 BTU | 60,000 | 82,500 |
| 1,600 sq ft | 32,000 | 2.67 | 36,000 BTU | 64,000 | 88,000 |
| 1,800 sq ft | 36,000 | 3 | 36,000 BTU | 72,000 | 99,000 |
| 2,000 sq ft | 40,000 | 3.33 | 48,000 BTU | 80,000 | 110,000 |
| 2,500 sq ft | 50,000 | 4.17 | 60,000 BTU | 100,000 | 137,500 |
By unit size
Already have a unit, or comparing two on a shelf? Each page works backwards from the BTU rating to the room it cools and heats, with kW, watts and tons. The squares are drawn to one scale: blue is the area it cools, orange the area it heats.
| Unit | Cools (average room) | Heats (moderate) | Heats (cold) | kW |
|---|---|---|---|---|
| 5,000 BTU | 250 sq ft | 120 sq ft | 90 sq ft | 1.47 |
| 6,000 BTU | 300 sq ft | 150 sq ft | 100 sq ft | 1.76 |
| 8,000 BTU | 400 sq ft | 200 sq ft | 140 sq ft | 2.34 |
| 9,000 BTU | 450 sq ft | 220 sq ft | 160 sq ft | 2.64 |
| 10,000 BTU | 500 sq ft | 250 sq ft | 180 sq ft | 2.93 |
| 12,000 BTU | 600 sq ft | 300 sq ft | 210 sq ft | 3.52 |
| 14,000 BTU | 700 sq ft | 350 sq ft | 250 sq ft | 4.10 |
| 15,000 BTU | 750 sq ft | 370 sq ft | 270 sq ft | 4.40 |
| 18,000 BTU | 900 sq ft | 450 sq ft | 320 sq ft | 5.28 |
| 24,000 BTU | 1,200 sq ft | 600 sq ft | 430 sq ft | 7.03 |
| 25,000 BTU | 1,250 sq ft | 620 sq ft | 450 sq ft | 7.33 |
| 30,000 BTU | 1,500 sq ft | 750 sq ft | 540 sq ft | 8.79 |
| 36,000 BTU | 1,800 sq ft | 900 sq ft | 650 sq ft | 10.55 |
By room type
Room-type pages apply the assumptions that actually fit that room: four people in a living room, the kitchen adder, poor insulation and tall ceilings in a garage, no solar gain in a basement.
What Size Air Conditioner Do You Need for a Bedroom?
Most bedrooms need a 5,000 to 8,000 BTU air conditioner. See the exact BTU for 100 to 250 sq ft bedrooms, and why quiet matters more than raw power.
What Size AC for a Master Bedroom or Primary Suite?
Master bedrooms of 250 to 500 sq ft usually need 6,000 to 12,000 BTU. Get the BTU for your suite including the en-suite bath and walk-in closet.
What Size Air Conditioner Does a Living Room Need?
Living rooms are the hardest room to size: people, sun, TVs and open kitchens all add load. Find the right BTU for 300 to 700 sq ft living spaces.
What Size AC for a Small or Home Office?
Home offices need 5,000 to 8,000 BTU for the room plus 400 to 1,500 BTU for computers and monitors. Size an office AC correctly, including equipment heat.
How Many BTU Does a Kitchen Air Conditioner Need?
Kitchens need the standard BTU for their size plus 4,000 BTU for the range, oven and refrigerator. See sized results for 100 to 400 sq ft kitchens.
How Many BTU to Cool a Sunroom, Florida Room, or Enclosed Porch?
Sunrooms need 30–40% more cooling than a normal room the same size. BTU figures for 150 to 500 sq ft sunrooms with the sun and insulation penalty applied.
What Size Air Conditioner for an Apartment?
Studios need 8,000–12,000 BTU; one-bedrooms 12,000–18,000 BTU across two units. Size an apartment AC by floor plan, floor level and window direction.
What Size AC or Fan Setup Works for a Dorm Room?
A dorm room needs 5,000–6,000 BTU: enough for 100–200 sq ft with two people, a mini fridge and laptops. What to buy and what housing offices allow.
How Many BTU Does a Garage Heater Need?
A 2-car garage needs 20,000–45,000 BTU depending on climate and insulation. BTU and wattage for 1, 2 and 3-car garages, electric vs gas.
How Many BTU to Heat a Basement?
Basements need less heat per sq ft than you would guess because the earth holds them near 50°F. BTU and wattage for 300 to 1,200 sq ft basements.