What Size Air Conditioner Do I Need for 1,500 Sq Ft?
1,500 sq ft is a 6,000 BTU/hr step on the room-AC chart, from 24,000 up to 30,000.
Full breakdown: BTU per square foot.
For a smaller whole space on a different method, see what size AC unit for 1,000 sq ft. The numbers below are only the ENERGY STAR room air conditioner rows at 1,500 sq ft.
Affiliate disclosure: as an Amazon Associate, we earn from qualifying purchases — at no cost to you.
Capacity from the chart
| Area to be cooled | Capacity needed | Source |
|---|---|---|
| 1,400 up to 1,500 sq ft | 24,000 BTU/hr | ENERGY STAR |
| 1,500 up to 2,000 sq ft | 30,000 BTU/hr | ENERGY STAR |
Put the step in scale. 30,000 minus 24,000 is 6,000 BTU/hr, and 6,000 BTU/hr is the whole capacity ENERGY STAR assigns to a 150 up to 250 sq ft room. Choosing the wrong side of 1,500 sq ft is not a small rounding error. It is an entire small-room unit of capacity. That is also why a central system for a 1,500 sq ft house should not be picked off this window-unit table.
How to size it
If the area is one room-sized zone cooled by room equipment, pick a side. Shade and ordinary occupancy: 24,000. Very sunny, or more than two people regularly: 30,000. Then apply the adjustment that matches, once.
| Adjustment | On the 24,000 row | On the 30,000 row | Source |
|---|---|---|---|
| Heavily shaded, reduce capacity 10% | 24,000 − 10% = 21,600 BTU/hr | 30,000 − 10% = 27,000 BTU/hr | ENERGY STAR |
| Very sunny, increase capacity 10% | 24,000 + 10% = 26,400 BTU/hr | 30,000 + 10% = 33,000 BTU/hr | ENERGY STAR |
| Each additional person beyond two | 24,000 + 600 BTU/hr = 24,600 BTU/hr | 30,000 + 600 BTU/hr = 30,600 BTU/hr | ENERGY STAR |
| Unit used in a kitchen | 24,000 + 4,000 BTU/hr = 28,000 BTU/hr | 30,000 + 4,000 BTU/hr = 34,000 BTU/hr | ENERGY STAR |
10% of 24,000 BTU/hr is 2,400 BTU/hr (24,000 × 10%).
10% of 30,000 BTU/hr is 3,000 BTU/hr (30,000 × 10%).
Shaded lower path: 24,000 − 10% = 21,600 BTU/hr, because 10% of 24,000 is 2,400. Sunny upper path: 30,000 + 10% = 33,000 BTU/hr, because 10% of 30,000 is 3,000. One person beyond two on the upper row is 30,000 + 600 = 30,600 BTU/hr. Kitchen use on the lower row is 24,000 + 4,000 = 28,000 BTU/hr. Kitchen use on the upper row is 30,000 + 4,000 = 34,000 BTU/hr. That last sum equals the chart's 34,000 capacity for a still larger area, but here it is kitchen arithmetic, not a change of floor area.
Buying 30,000 for a shaded area that should have started at 24,000 and then dropped 10% leaves a unit that satisfies the thermostat before it dries the air. ENERGY STAR's phrase for that air is "cool, moist air will make the room feel damp and clammy."
The ceiling under these rows is 8-foot. Higher than that, select a room air conditioner with a higher CADR. The chart does not print a replacement capacity for the taller room.
30,000 BTU window air conditioners on Amazon Window air conditioner support brackets on Amazon
Related questions
- What size air conditioner for 1,200 sq ft
- What size air conditioner for 2,000 sq ft
- What size air conditioner for 800 sq ft
All of these questions are listed on the topic map.
Sources
- ENERGY STAR, Room Air Conditioners — https://www.energystar.gov/products/room_air_conditioners — accessed Oct 2, 2026.
Frequently asked questions
What size air conditioner for 1,500 sq ft?
1,400 up to 1,500 sq ft is 24,000 BTU/hr. 1,500 up to 2,000 sq ft is 30,000 BTU/hr. Heavy shade supports the 24,000 start. Sun or more than two people regularly supports the 30,000 start.
How large is that boundary step?
30,000 − 24,000 = 6,000 BTU/hr. That difference equals the entire capacity of the 150 up to 250 sq ft row. Ten percent of 24,000 is 2,400, so the shaded lower path is 21,600 BTU/hr.
What if someone buys 30,000 BTU/hr for a shaded 1,500 sq ft area?
That skips the lower row and the shade cut. ENERGY STAR says a unit that is too big cools the room before it removes humidity, and "cool, moist air will make the room feel damp and clammy." The sunny upper path is the one that starts at 30,000 and then adds 10% to reach 33,000 BTU/hr.
Is this the right chart for a 1,500 sq ft house?
Only for a room air conditioner, and only on an 8-foot ceiling. A central system should get a load calculation on the HVAC load calculator. The 1,000 sq ft guide is a different method for a smaller whole space.