How the BTU Air Conditioner Formula Works
Air conditioner sizing is based on thermodynamic volume calculations rather than simple floor area alone. The baseline requirement for standard residential spaces is calculated using:
Baseline BTU = Room Volume (m³) × 180 BTU/m³
Where Room Volume is Length × Width × Height in meters. For imperial measurements, the baseline rule is approximately 20 to 25 BTU per square foot of area for standard 8-foot ceilings.
Standard Room Size vs Air Conditioner Capacity Reference
Use this quick reference guide for typical residential bedrooms and living spaces with 2.8m ceiling heights:
| Room Dimensions | Floor Area | Recommended BTU | AC Size (PK) | US Tons |
|---|---|---|---|---|
| 3 × 3 meters | 9 m² (97 sq ft) | 5,000 BTU | 1/2 PK | 0.42 Ton |
| 3 × 4 meters | 12 m² (129 sq ft) | 7,000 BTU | 3/4 PK | 0.58 Ton |
| 4 × 4 meters | 16 m² (172 sq ft) | 9,000 BTU | 1 PK | 0.75 Ton |
| 4 × 5 meters | 20 m² (215 sq ft) | 12,000 BTU | 1.5 PK | 1.0 Ton |
| 5 × 6 meters | 30 m² (323 sq ft) | 18,000 BTU | 2 PK | 1.5 Tons |
| 6 × 7 meters | 42 m² (452 sq ft) | 24,000 BTU | 2.5 PK | 2.0 Tons |