❄ Interactive AC Tonnage & BTU Sizing Calculator
Enter your room dimensions and environmental factors to determine required cooling power.
How AC Tonnage and BTU are Calculated
In HVAC (Heating, Ventilation, and Air Conditioning) engineering, cooling capacity is measured in BTUs per hour (British Thermal Units) or in Tons of Refrigeration:
- 1 Ton of Air Conditioning = 12,000 BTU per hour.
- Baseline Rule: Standard residential spaces require approximately 20 to 25 BTU per square foot of floor area under normal climate conditions.
Standard Room Sizing Reference Table
| Room Square Footage | Estimated BTU Requirement | Recommended AC Tonnage |
|---|---|---|
| Up to 120 sq ft (11 m²) | 5,000 " 6,000 BTU | 0.8 Ton (Window or Mini-Split) |
| 121 to 160 sq ft (11"15 m²) | 7,500 " 9,000 BTU | 1.0 Ton (Standard Small Bedroom) |
| 161 to 240 sq ft (15"22 m²) | 12,000 " 14,000 BTU | 1.5 Ton (Master Bedroom / Living Room) |
| 241 to 350 sq ft (22"32 m²) | 18,000 " 20,000 BTU | 2.0 Ton (Spacious Lounge / High Ceiling) |
| 351 to 500 sq ft (32"46 m²) | 24,000 " 28,000 BTU | 2.5 Ton (Open Concept Family Great Room) |
Why Proper Sizing Matters
The Danger of Oversizing: When an air conditioner is too large for the room, it cools the temperature very quickly and turns off before it has completed a full dehumidification cycle. This creates a cold, clammy, humid atmosphere that promotes mold growth.
The Danger of Undersizing: If the unit is too small, its compressor runs continuously at full power on hot summer days, drastically inflating your electricity bill without ever reaching your set thermostat temperature.