AC BTU Calculator: 10 × 10 ft room
Size a room air conditioner in BTU from the room size, sun exposure and occupants — and see the unit size to buy.
// Bill of materials
Costs are rough, materials only — edit the price to match your quote.
Pre-filled for a 10 × 10 ft room. Change any value to recalculate, or start from scratch.
How it's calculated
Base cooling = area × 25 BTU per square foot, scaled by ceiling height. We adjust for sun exposure, add 600 BTU for each occupant beyond two, and add 4,000 BTU for a kitchen. The recommended unit rounds up to the next 1,000 BTU.
Worked example — 10 × 10 ft room
- Room width
- 10 ft
- Room length
- 10 ft
- Ceiling height
- 8 ft
- Sun exposure
- Average
- Regular occupants
- 2 count
- Room type
- Not a kitchen
Nearby sizes
| Room size | Recommended unit | |
|---|---|---|
| 8 × 8 ft room | 2,000 BTU | Open |
| 8 × 10 ft room | 2,000 BTU | Open |
| 8 × 12 ft room | 3,000 BTU | Open |
| 10 × 10 ft room (this page) | 3,000 BTU | |
| 10 × 12 ft room | 3,000 BTU | Open |
| 10 × 14 ft room | 4,000 BTU | Open |
| 10 × 16 ft room | 4,000 BTU | Open |
| 12 × 12 ft room | 4,000 BTU | Open |
| 12 × 14 ft room | 5,000 BTU | Open |
| 12 × 16 ft room | 5,000 BTU | Open |
| 12 × 18 ft room | 6,000 BTU | Open |
| 12 × 20 ft room | 6,000 BTU | Open |
Tips for buying ac btu
- Bigger isn't better — an oversized AC short-cycles, cools unevenly and never dehumidifies properly.
- About 25 BTU per square foot is the rule of thumb; sun, ceilings and occupants nudge it up or down.
- Add roughly 4,000 BTU for a kitchen — appliances throw off a lot of heat.
- A very sunny room needs about 10% more; a heavily shaded one about 10% less.
- For whole-home cooling, size with a professional Manual J load calculation, not a room rule of thumb.
- Check the unit's voltage — larger window and portable units often need a dedicated circuit.
Frequently asked questions
What size AC do I need for a 12x14 room?
A 12×14 room (168 sq ft) needs about 4,200 BTU, so a 5,000 BTU unit is the common pick. Sun, occupants and a kitchen push that higher.
How many BTU per square foot for air conditioning?
About 25 BTU per square foot is the standard starting point. This calculator adjusts that for ceiling height, sun, occupants and kitchens.
Is a bigger AC better?
No. An oversized unit cools too fast, cycles on and off, and leaves the room clammy because it doesn't run long enough to remove humidity.
Does sun exposure matter?
Yes. A very sunny room needs roughly 10% more cooling; a shaded one about 10% less. Pick your exposure and we adjust.