AC Tonnage Calculator
Size your air conditioner correctly based on area and climate
Floor area to be cooled
Standard: 8 ft
Affects BTU per sq ft
BTUs
—
BTU/h
Tonnage
—
tons
Estimated Cost
—
USD
Disclaimer: Results are estimates based on standard formulas. Not a substitute for professional advice from a licensed contractor, engineer, or architect. Verify all calculations before making purchasing or construction decisions.
How to Use This Calculator
Properly sizing an air conditioner is critical for comfort, efficiency, and equipment life. An undersized unit runs constantly, while an oversized one short-cycles and fails to dehumidify.
- Measure the total floor area you need to cool
- Enter your ceiling height (standard is 8 ft)
- Select your climate zone for accurate BTU loading
- Use the tonnage result to shop for matching AC equipment
Expert Insights
Smart analysis for your HVAC project
Climate Load Adjustment
Hot humid climates need ~30 BTU/sq ft, while cooler regions need only 20. AI scales tonnage based on your local climate factor.
Ceiling Height Factor
Taller ceilings mean more volume to cool. AI multiplies load by (ceiling height / 8) to account for high-ceiling homes.
Dehumidification Check
In humid regions, slightly smaller units run longer and remove more moisture. AI flags oversized results that hurt dehumidification.
Calculation Formula
Climate factor = Hot Humid: 30 | Mild: 25 | Cold: 20 BTU/sq ft
BTUs = Area x (Ceiling Height / 8) x Climate factor
Tonnage = ceil(BTUs / 12,000 x 10) / 10
Estimated Cost = ceil(Tonnage x $3,000)
AC System Comparison
| System Type | Tonnage Range | Cost per Ton | SEER Rating | Best For |
|---|---|---|---|---|
| Central Split AC | 1.5-5 tons | $2,500-3,500 | 14-16 | Whole-home cooling |
| Heat Pump | 1.5-5 tons | $3,000-4,500 | 15-18 | Heating + cooling |
| Ductless Mini-Split | 0.5-2 tons | $3,500-5,000 | 18-22 | Zoned rooms |
| Packaged Unit | 2-5 tons | $3,000-4,000 | 14-16 | Small commercial |
Authority References
Our calculations are based on guidelines and standards from these authoritative sources:
- ACCA (Air Conditioning Contractors of America) — Manual J Residential Load Calculation. Learn more
- Department of Energy (DOE) — Right-Sized Air Conditioners. Learn more
- AHRI (Air-Conditioning, Heating, and Refrigeration Institute) — Equipment Certification Directory. Learn more
Frequently Asked Questions
How many square feet does a 1 ton AC cover?
A 1-ton AC (12,000 BTU/h) typically covers 400-600 sq ft, depending on ceiling height, insulation, and climate. Hot humid climates need closer to 400 sq ft per ton.
How is AC tonnage calculated?
AC tonnage is calculated by dividing the cooling load in BTUs by 12,000. Cooling load = area x (ceiling height / 8) x climate factor (20-30 BTU/sq ft).
What happens if my AC is oversized?
Oversized units short-cycle, reducing dehumidification, increasing energy bills, and shortening equipment life. Proper sizing improves comfort and efficiency.