What changes the size for a 150 ft² room
150 ft² is about 12 × 12 ft, or 15 × 10 ft, or 13 × 12 ft. The base capacity is for an average room, and the table adjusts it for the things that add or remove heat:
| Conditions | BTU needed | Shop for |
|---|---|---|
| Average room (2 people, 8 ft ceiling) | 5,000 BTU | 5,000 BTU |
| Heavily shaded room | 4,500 BTU | 5,000 BTU |
| Very sunny room | 5,500 BTU | 6,000 BTU |
| 4 people regularly in the room | 6,200 BTU | 8,000 BTU |
| It is a kitchen | 9,000 BTU | 10,000 BTU |
| 10 ft ceilings | 6,300 BTU | 8,000 BTU |
What kind of air conditioner is that?
A unit this size is a small window air conditioner or a small portable unit, and it runs on a standard 120 V household outlet.
Bigger is not better: an oversized unit cools the room quickly, shuts off, and leaves it clammy. See the full sizing guide for window, portable and mini-split options.
Want to change anything else? The calculator above is the full AC Size Calculator (BTU): edit any number and the results update instantly.
Tools & materials for this project
As an Amazon Associate we earn from qualifying purchases. These links do not change what you pay.
Frequently asked questions
What size air conditioner for 150 square feet?
About 5,000 BTU per hour, so shop for a 5,000 BTU unit. That is 0.42 tons of cooling, based on Energy Star room-size guidance for an average room.
Is a 5,000 BTU air conditioner enough for 150 sq ft?
Yes for an average room with 8 ft ceilings and two people. A very sunny room would need about 5,500 BTU, and a kitchen about 9,000 BTU, so size up in those cases.
What if my 150 sq ft room has high ceilings?
With 10 ft ceilings, the same 150 ft² needs about 6,300 BTU (8,000 BTU), because there is more air to cool.
Related sizes and guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.