AC Tonnage Calculator
Air conditioners are sized in 'tons' — one ton equals 12,000 BTU/hr of cooling capacity. This calculator helps you find the right size unit based on your space and conditions.
Enter Your Measurements
Results
Enter your measurements to see results
How to Use This Calculator
- Enter the total square footage to be cooled.
- Select your climate zone.
- Enter ceiling height if non-standard.
- Review the recommended unit size.
How AC Tonnage Calculation Works
This calculator divides your square footage by a climate-adjusted factor (400–550 sq ft per ton) to estimate cooling tonnage. The ceiling height multiplier accounts for additional air volume in rooms with tall ceilings. The result is rounded to the nearest standard AC unit size. Standard residential units come in 1.5, 2, 2.5, 3, 3.5, 4, and 5 ton sizes.
Formula
Tons = Square Footage ÷ (Sq ft per ton for climate zone) × (Ceiling Height ÷ 8). Round to nearest standard size: 1.5, 2, 2.5, 3, 3.5, 4, or 5 tons.
Frequently Asked Questions
What does '1 ton' of cooling mean?
One ton of cooling equals 12,000 BTU/hr — the amount of heat needed to melt one ton (2,000 lbs) of ice in 24 hours. A 3-ton AC unit removes 36,000 BTU of heat per hour.
How many square feet does 1 ton of AC cover?
Roughly 400–600 sq ft depending on climate, insulation, and construction. Hot climates need about 400 sq ft/ton; cold climates about 550 sq ft/ton.
Is it better to size up or down?
Neither — size to the calculation. Oversizing causes short-cycling, humidity problems, and higher costs. Undersizing means the system can't keep up on the hottest days.