Industry Guide
HVAC Sizing: BTU, Tons, and Room Size Guide
Calculate the right heating and cooling capacity for any room or building.
Last updated: 2026-03-15
Key HVAC Conversions
- 1 ton of cooling = 12,000 BTU/hr
- 1 BTU = 1,055.06 joules
- 1 ton = 3.517 kW (thermal)
- 1 horsepower (refrigeration) = 4,714 BTU/hr
Room BTU Requirements (Cooling)
| Room Size (sq ft) | BTU Needed | Tons |
|---|---|---|
| 100-150 | 5,000 | 0.42 |
| 150-250 | 6,000 | 0.50 |
| 250-350 | 8,000 | 0.67 |
| 350-450 | 10,000 | 0.83 |
| 450-550 | 12,000 | 1.0 |
| 550-700 | 14,000 | 1.17 |
| 700-1,000 | 18,000 | 1.5 |
| 1,000-1,400 | 24,000 | 2.0 |
| 1,400-1,800 | 30,000 | 2.5 |
| 1,800-2,500 | 36,000-42,000 | 3.0-3.5 |
Adjustment Factors
- Heavy shade: reduce BTU by 10%
- Heavy sun exposure: increase by 10%
- Kitchen: add 4,000 BTU
- Each additional person: add 600 BTU
- High ceilings (over 8 ft): increase by 20%
- Poor insulation: increase by 15-25%
Tons to BTU Reference
| Tons | BTU/hr | kW (thermal) | Typical Home Size |
|---|---|---|---|
| 1.5 | 18,000 | 5.28 | 600-900 sq ft |
| 2.0 | 24,000 | 7.03 | 900-1,400 sq ft |
| 2.5 | 30,000 | 8.79 | 1,400-1,800 sq ft |
| 3.0 | 36,000 | 10.55 | 1,800-2,200 sq ft |
| 4.0 | 48,000 | 14.07 | 2,200-3,000 sq ft |
| 5.0 | 60,000 | 17.58 | 3,000-3,800 sq ft |
Convert energy units with our energy converter.