What size air conditioner for 1000 sq ft? BTU answer and adjustments
For 1000 square feet, the baseline is 20,000 BTU/h (20 BTU per sq ft) — about 1.67 tons or 5.9 kW of cooling. Adjust to 22,000 BTU for a sun-baked room, 18,000 for a shaded one, 24,000 if it is a kitchen, and add 600 BTU per regular occupant beyond two.
| Scenario | Rule | BTU/h |
|---|---|---|
| Baseline room | 1000 × 20 | 20,000 |
| Very sunny | +10% | 22,000 |
| Heavily shaded | −10% | 18,000 |
| Kitchen | +4,000 | 24,000 |
| Four regular occupants | +600 × 2 | 21,200 |
Conversions: 12,000 BTU/h = 1 ton = 3.517 kW. 20,000 BTU/h ≈ 1.67 tons ≈ 5.9 kW. Figures are cooling capacity to look for on the spec sheet, not electrical input.
Matching a real machine
In equipment terms, 1000 sq ft points to an 18,000–24,000 BTU mini-split, or central/ducted equipment for enclosed layouts. Round to the next available size above your adjusted number — never two sizes up: an oversized unit cools fast, stops before dehumidifying, and leaves the room cold and clammy.
Method and the Manual J threshold in our BTU sizing guide; equipment options on window units, mini-splits and portables (read SACC, not marketing BTU).
Frequently asked questions
How many BTU for 1000 square feet?
20,000 BTU/h as a baseline (20 BTU/sq ft), 22,000 for a very sunny room, 18,000 for a shaded one, plus 4,000 for a kitchen and 600 per occupant beyond two. That is about 1.67 tons or 5.9 kW.
What size AC unit is that?
An 18,000–24,000 BTU mini-split, or central/ducted equipment for enclosed layouts. For whole-house systems serving several enclosed rooms, a Manual J load calculation replaces this room-level rule.
Is 20 BTU per square foot always right?
It is the room-unit baseline ENERGY STAR and the DOE use; ceiling height above 8 ft, poor insulation and big west glazing push it higher, while a well-insulated shaded room can sit lower. The adjustments above capture the common cases.