Full catalog
All the HVAC tools.
Sizing, cost, efficiency, ductwork, refrigerant, and pro electrical tools. Built by HVAC experts.
Start here
US climate zone map
IECC zone, design temperatures, R-value targets, and HDD/CDD by ZIP. Useful before you open a sizing tool below.
System sizing
Get the right tonnage. Stop oversizing.
- BTU sizing calculator
- Climate zone map
- AC tonnage calculator
- and more
Cost & ROI
Real numbers, real bills, real payback.
- HVAC replacement cost
- Heat pump vs gas furnace
- SEER2 savings calculator
- and more
Efficiency
Decode the ratings that actually matter.
- SEER to SEER2 converter
- HSPF to HSPF2 converter
- EER vs SEER calculator
- and more
Ductwork & airflow
Free duct math that used to cost $400.
- Duct sizing (Manual D)
- Static pressure calculator
- CFM calculator
- and more
Refrigerant
R-410A, R-32, R-454B. All the math.
- Refrigerant charge calculator
- AC recharge cost calculator
- Superheat calculator
- and more
Pro tools
For technicians and serious DIYers.
- HVAC unit converter
- Wire size calculator
- Breaker size calculator
- and more