Room Dimensions

Enter the dimensions of your room in feet

Length (feet)

Width (feet)

Height (feet)

Understanding AC Size Calculations

BTU Basics

A British Thermal Unit (BTU) measures how much heat an AC unit can remove per hour. One ton of cooling equals 12,000 BTUs.

Tonnage Conversion

Professional HVAC systems are rated in tons: • 1.5 to 5 tons for homes • Larger units for commercial spaces

Efficiency Factors

Proper sizing ensures optimal performance, energy efficiency, and comfort while maintaining humidity control.

Professional Sizing Considerations

Square Footage Basics

Measure room length and width precisely
Account for irregular room shapes
Include connected spaces that share airflow
Consider open floor plans
Exclude uninsulated spaces

Additional Factors

Window quantity and exposure
Insulation quality
Occupancy patterns
Heat-generating appliances
Local climate conditions

AC Size Reference Guide

Room Size	Required BTUs	Tonnage	Typical Application
Up to 150 sq ft	5,000	0.4	Small bedroom/office
150-250 sq ft	6,000	0.5	Medium bedroom
250-350 sq ft	8,000	0.7	Large bedroom
350-450 sq ft	10,000	0.8	Living room
450-550 sq ft	12,000	1.0	Open concept space
550-1,000 sq ft	18,000	1.5	Small apartment
1,000-1,200 sq ft	21,000	1.75	Small home
1,200-1,400 sq ft	23,000	2.0	Medium home

Advanced Sizing Factors

Insulation Quality

Superior (R-30+): Reduce BTUs by 10-15%
Standard (R-19 to R-29): Base calculation
Poor (R-18 or lower): Increase BTUs by 15-20%

Window Exposure

South-facing: Add 15% BTUs
West-facing: Add 12% BTUs
East-facing: Add 10% BTUs
North-facing: Add 5% BTUs

Occupancy

Additional occupants: 600 BTUs per person
Regular guests: 400 BTUs per visitor
Active spaces: Extra 200 BTUs per person

Equipment Heat

Kitchen appliances: 4,000-6,000 BTUs
Computers: 1,000 BTUs each
TVs: 500-1,000 BTUs each
Exercise equipment: 800 BTUs per machine

Frequently Asked Questions

How do I calculate the right AC size for my room?

To calculate the right AC size, measure your room's length, width, and height. Use our calculator to factor in climate, insulation, and usage patterns for accurate BTU requirements.

What happens if I install an oversized AC unit?

An oversized AC unit leads to frequent cycling, higher energy bills, inadequate dehumidification, and increased wear and tear on the system.

How does climate affect AC size requirements?

Climate significantly impacts AC sizing. Hot, humid climates require larger units, while moderate climates can use smaller ones. Our calculator accounts for your specific climate zone.

What role does insulation play in AC sizing?

Good insulation reduces cooling requirements by up to 30%. Poor insulation means you'll need a larger AC unit to maintain desired temperatures.

How often should I resize my AC needs?

Recalculate your AC needs if you make significant changes to your space, such as adding insulation, changing windows, or modifying room usage.

What's the difference between BTU and tonnage?

BTU (British Thermal Unit) measures cooling power. One ton of cooling equals 12,000 BTUs per hour. A 2-ton AC unit provides 24,000 BTUs of cooling.

Should I consider ceiling height in AC sizing?

Yes, ceiling height affects room volume and cooling requirements. Rooms with high ceilings need larger AC units to maintain comfortable temperatures.

How do windows affect AC size requirements?

Windows can significantly impact AC sizing. Large or numerous windows increase solar heat gain, requiring a larger AC unit for effective cooling.

What's the impact of room orientation on AC needs?

South and west-facing rooms typically require more cooling power due to increased sun exposure. Our calculator considers these factors for accurate sizing.

Can I use the same calculations for different room types?

Different room types have varying cooling needs. Kitchens and computer rooms typically need more cooling than bedrooms due to heat-generating appliances and equipment.

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Last updated: 5/11/2025

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