❄️ AC Tonnage Calculator
Calculate the right AC tonnage (BTU) for your home
Total cooled area of your home
Windows gain heat and increase cooling needs
Each person adds ~400 BTU of heat
How to Use This Calculator
Enter Home Square Footage
Input the total cooled square footage of your home. This is the area that needs cooling, excluding unheated spaces like garages.
Enter Ceiling Height
Input the average ceiling height in feet (standard is 9 feet). Higher ceilings require more cooling capacity.
Select Climate and Insulation
Choose your climate zone (hot, moderate, mild) and insulation quality (poor, average, good). These factors significantly affect cooling requirements.
Add Windows and Occupants
Enter the number of large windows and number of occupants. Windows gain heat and occupants generate heat, increasing cooling needs.
Calculate and Review
Click "Calculate AC Tonnage" to see recommended AC size in tons and BTU, closest standard size, and estimated cost. Consult an HVAC professional for accurate sizing.
Formula
BTU per sq ft = Base BTU (varies by climate and insulation)
Base BTU = Square Footage × BTU per sq ft
Adjusted BTU = Base BTU × (Ceiling Height ÷ 9) × Window Factor + Occupant BTU
Recommended BTU = Round up to nearest 5,000 BTU
Tons = BTU ÷ 12,000 (1 ton = 12,000 BTU)
Example 1: Moderate Climate, Average Insulation (2000 sq ft, 9 ft ceilings, 2 occupants)
Step 1: BTU per sq ft: 20 BTU/sq ft (moderate climate, average insulation)
Step 2: Base BTU: 2000 × 20 = 40,000 BTU
Step 3: Adjusted for ceiling: 40,000 × (9/9) = 40,000 BTU
Step 4: Add occupants: 40,000 + (2 × 400) = 40,800 BTU
Step 5: Round up: 45,000 BTU (3.75 tons, round to 4 tons)
Example 2: Hot Climate, Poor Insulation (2500 sq ft, 10 ft ceilings, 12 windows, 4 occupants)
Step 1: BTU per sq ft: 30 BTU/sq ft (hot climate, poor insulation)
Step 2: Base BTU: 2500 × 30 = 75,000 BTU
Step 3: Adjusted for ceiling: 75,000 × (10/9) = 83,333 BTU
Step 4: Adjusted for windows: 83,333 × 1.6 = 133,333 BTU
Step 5: Add occupants: 133,333 + (4 × 400) = 134,933 BTU
Step 6: Round up: 135,000 BTU (11.25 tons, round to 11.5 tons)
About AC Tonnage Calculator
The AC Tonnage Calculator is an essential tool for homeowners, contractors, and HVAC professionals who need to determine the right air conditioning tonnage (BTU) for home cooling. This calculator eliminates guesswork by providing precise AC sizing calculations based on square footage, ceiling height, climate zone, insulation quality, windows, and occupants, helping you select the right AC size for efficient and effective cooling.
When to Use This Calculator
- New AC Installation: Calculate AC tonnage needed for new AC installations
- AC Replacement: Determine correct AC size when replacing existing AC
- Home Addition: Calculate additional cooling capacity needed for home additions
- Budget Planning: Estimate AC costs based on required size
- HVAC Planning: Plan HVAC systems for new construction or renovations
Why Use Our Calculator?
- ✅ Accurate Sizing: Precise calculations prevent undersizing or oversizing
- ✅ Multiple Factors: Considers climate, insulation, ceiling height, windows, and occupants
- ✅ Standard Sizes: Recommends closest standard AC tonnage size
- ✅ Cost Estimation: Provides estimated costs based on AC size
- ✅ Comprehensive Results: Shows BTU, tons, and cubic footage
- ✅ Time Savings: Instant calculations eliminate manual math and measurements
Common Applications
New AC Installation: Homeowners and contractors installing new AC systems use this calculator to determine correct AC tonnage. Proper sizing ensures efficient cooling and energy savings while preventing undersizing or oversizing.
AC Replacement: Homeowners replacing existing AC units use this tool to verify or recalculate AC size. Home improvements like better insulation may allow for smaller AC units, while additions may require larger AC units.
Budget Planning: Homeowners and contractors use this calculator to estimate AC costs based on required size, helping plan budgets and compare options.
Tips for Best Results
- Measure Accurately: Measure cooled square footage accurately (exclude unheated spaces)
- Consider All Factors: Account for climate, insulation, ceiling height, windows, and occupants
- Sun Exposure: Consider sun exposure - south-facing windows need more cooling
- Consult Professional: Always consult an HVAC professional for accurate sizing and installation
- Energy Efficiency: Consider energy-efficient AC units for lower operating costs
- Ductwork: Ensure ductwork can handle AC size
Frequently Asked Questions
What size AC do I need for a 2000 sq ft home?
For a 2000 sq ft home in a moderate climate with average insulation, you typically need 3-4 tons (36,000-48,000 BTU). Actual size depends on climate, insulation, ceiling height, windows, and occupants. Use the calculator with your specific details for accurate sizing.
How many BTUs per square foot do I need for AC?
BTU per square foot varies by climate and insulation: 16-20 BTU/sq ft for mild climates, 18-25 BTU/sq ft for moderate climates, and 22-30 BTU/sq ft for hot climates. Better insulation reduces BTU requirements. The calculator adjusts for these factors.
Can an AC be too big?
Yes! An oversized AC cycles frequently, reducing efficiency, increasing wear, and creating temperature swings. It doesn't dehumidify properly because it cools too quickly. Undersizing causes inadequate cooling. Proper sizing is essential for efficiency and comfort. Always consult an HVAC professional.
What are standard AC sizes?
Standard AC sizes are typically 1.5, 2, 2.5, 3, 3.5, 4, 5, and 6 tons (18,000 to 72,000 BTU). The calculator recommends the closest standard size to your requirements.
How do I convert BTU to tons?
Divide BTU by 12,000 to get tons (1 ton = 12,000 BTU). For example, 48,000 BTU ÷ 12,000 = 4 tons. The calculator automatically converts BTU to tons for easy reference.
Should I consult a professional?
Yes! While this calculator provides estimates, AC sizing is complex and requires professional assessment. An HVAC professional considers many additional factors like ductwork, windows, sun exposure, construction type, and local codes for accurate sizing and installation.