Kitchens get a flat 4,000 BTU added on top of the 20 BTU per square foot base, and that number is not arbitrary. A gas range burner puts out 9,000 to 12,000 BTU/hr while it is on, an electric oven at 350°F leaks 1,500 to 2,500 BTU/hr into the room, and a refrigerator rejects several hundred BTU/hr continuously. Averaged over a cooking evening, 4,000 BTU is a reasonable stand-in for all of it. For a small 120 sq ft galley kitchen that is more than double the room's own load, which is why kitchens feel like the hottest room in the house.
The table below already includes the kitchen adder. Notice that even the smallest kitchen lands at 6,000 to 8,000 BTU, and a 300 sq ft eat-in kitchen wants 10,000 BTU. If the kitchen is open to the living room, do not size the kitchen alone; go to the living room page and size the combined space with the kitchen box ticked.
One caution: a window air conditioner in a kitchen will pull in grease-laden air and its filter needs cleaning far more often than a bedroom unit. A mini-split head mounted high on a wall away from the range holds up much better, and a range hood that actually vents outdoors (not a recirculating one) removes heat and moisture at the source before the AC has to deal with it.
Cooling BTU by kitchen size
Baseline: average sun, average insulation, moderate climate, 8 ft ceiling, 2 people, kitchen included.
| Floor area | Best case | Baseline | Worst case | Unit to buy |
|---|---|---|---|---|
| 100 sq ft | 5,600 | 6,000 | 6,500 | 6,000 BTU |
| 150 sq ft | 6,400 | 7,000 | 7,800 | 8,000 BTU |
| 200 sq ft | 7,200 | 8,000 | 9,100 | 8,000 BTU |
| 250 sq ft | 8,100 | 9,000 | 10,300 | 10,000 BTU |
| 300 sq ft | 8,900 | 10,000 | 11,600 | 10,000 BTU |
| 400 sq ft | 10,500 | 12,000 | 14,100 | 12,000 BTU |
Best case = good insulation and heavy shade; worst case = poor insulation and full sun.
Kitchen-specific advice
Vent the range hood outside
A ducted range hood at 200–400 CFM removes cooking heat and steam directly. It is the single most effective way to make a kitchen AC feel bigger than it is.
Do not oversize to fight cooking peaks
The 4,000 BTU adder already covers normal cooking. Sizing for Thanksgiving means a unit that short-cycles the other 364 days. Open a window or run the hood during a big cook instead.
Skip portable units in kitchens if you can
Portable ACs pull room air past a hot condenser and their intake filters clog with grease quickly. If a portable is the only option, clean the filter every two weeks in cooking season.
Common questions
Why do kitchens need more BTU than other rooms?
Cooking appliances and the refrigerator release heat continuously. The industry adds a flat 4,000 BTU for a kitchen regardless of size, which for small kitchens can more than double the base load.
How many BTU for a 200 sq ft kitchen?
About 8,000 BTU: 200 × 20 = 4,000 for the room plus 4,000 for the kitchen appliances. Shop for an 8,000 BTU unit, or 10,000 BTU if the kitchen is sunny or poorly insulated.