What size AC do I need? Why won't my furnace start? Is a heat pump worth it?
Free HVAC calculators, sizing guides, and troubleshooting help — with the reasoning shown, not just a recommendation.
Professional HVAC Calculators & Sizing Tools
Size your HVAC equipment correctly with our ACCA Manual J based calculators. Avoid oversizing, reduce energy costs, and ensure optimal comfort with professional-grade sizing tools.
AC BTU Calculator
Calculate exact cooling capacity for any room size. Factors in climate zone, insulation, windows, and heat sources.
AC Tonnage Calculator
Convert BTUs to tons and size central AC systems. Includes ductwork considerations and SEER ratings.
SEER2 Savings Calculator
Compare energy costs between different SEER2 ratings. Calculate ROI and payback period for upgrades.
Heat Pump Size Calculator
Size heat pumps for both heating and cooling. Includes cold climate considerations and backup heat.
Furnace Sizing Calculator
Calculate furnace BTU requirements. Factors in home size, insulation, climate zone, and heat loss.
Mini Split Sizing
Size ductless mini splits for single or multi-zone applications. Includes line set calculations.
All calculators updated for 2026 efficiency standards and include regional climate adjustments
Complete HVAC System Guides & Resources
Whether you're replacing equipment, troubleshooting problems, or comparing options, our comprehensive guides provide the technical details and real-world insights you need.
Air Conditioning Systems
Heating Systems
Energy Efficiency & Ratings
Indoor Air Quality
Quick HVAC Answers & Common Questions
Sizing Questions
Cost Questions
Efficiency Questions
Troubleshooting
Compare HVAC Brands & Reviews
Explore detailed comparisons of top HVAC brands including Carrier, Trane, Lennox, Goodman, and more. Compare manufacturer warranty terms, AHRI-certified efficiency ratings, and price tiers.
View All Brand ComparisonsSmart HVAC Technology & Controls
Optimize comfort and efficiency with smart thermostats and zoning systems for precise climate control.
Smart Thermostats
Wi-Fi enabled thermostats with learning algorithms, remote control, and energy reports.
Zoning Systems
Control temperature independently in different areas for maximum comfort and efficiency.
HVAC Resources & Tools
Troubleshooting
Cost Guides
How We Source Our Content
We provide HVAC information based on manufacturer data, industry standards, and AHRI-certified efficiency ratings — no affiliate links or paid product placements.
Data-Driven Content
Guides reference AHRI certifications, DOE data, and ACCA Manual J methods where applicable
Industry Standards
Following ASHRAE, ACCA, EPA, and ENERGY STAR guidelines in all recommendations
Reviewed and Updated Regularly
Content is refreshed as standards, tax law, and equipment specifications change
Our Editorial Standards
Research Process
- Verify all specifications against AHRI Directory
- Cross-reference EPA ENERGY STAR databases
- Use ACCA Manual J for all sizing calculations
- Include regional climate zone variations
Independence Commitment
- No affiliate links or referral fees
- No manufacturer sponsorships
- Equal coverage of all major brands
- Transparent about limitations and assumptions
Start With Our Most Popular Calculator
Size your AC correctly and avoid the #1 HVAC mistake: oversizing. Our calculator uses ACCA Manual J methodology for accurate results.