Why Correct AC Sizing Matters
Selecting the right size of air conditioner is crucial for both comfort and efficiency. An undersized unit will struggle to cool the space, leading to higher energy bills and wear on the system. On the other hand, an oversized unit may cool the room too quickly without properly dehumidifying, resulting in discomfort and wasted energy.
Factors Affecting Cooling Load
The cooling requirement of a room depends on multiple factors, including:
- Room volume – Larger rooms require more cooling capacity.
- Occupancy – Each additional person adds to the heat load.
- Appliances and equipment – Devices like computers, TVs, and refrigerators emit heat.
- Windows and sunlight – Rooms with more or larger windows gain more heat.
- Insulation and orientation – Poor insulation or west-facing rooms exposed to the sun increase cooling demand.
How the Calculator Works
The calculator above uses rule-of-thumb estimations for heat load:
- Room load: based on room volume (BTU/hr per cubic foot).
- Occupancy load: ~600 BTU/hr per person.
- Appliance load: converted from watts to BTU/hr.
- Window load: estimated per window.
The total load in BTU/hr is then converted to tons of refrigeration (1 Ton = 12,000 BTU/hr). Based on the calculation, the tool suggests the nearest standard AC tonnage size.
Common AC Sizes and Applications
- 0.75 – 1 Ton: Small bedrooms or study rooms (up to ~120 sq. ft.).
- 1.5 Ton: Medium bedrooms or small living rooms (120–180 sq. ft.).
- 2 Ton: Larger living rooms or offices (180–250 sq. ft.).
- 2.5 – 3 Ton: Halls, conference rooms, or larger commercial spaces.
- 4 – 5 Ton: Very large halls or industrial areas (consult an HVAC engineer).
Important Note
This calculator provides a general guideline based on typical assumptions. Actual cooling requirements can vary depending on insulation quality, ceiling height, climate conditions, and room orientation. For precise sizing, consult a qualified HVAC engineer who can perform a detailed heat load analysis.
