HVAC tools and guides for homeowners.
Size your system, check a repair quote, and fix common problems. The same math a contractor runs, free and in plain English.
Most used tools
Six categories
Find the right tool.
Sizing for homeowners, refrigerant math for pros, and everything in between.
System sizing
Get the right tonnage. Stop oversizing.
ExploreCost & ROI
Real numbers, real bills, real payback.
ExploreEfficiency
Decode the ratings that actually matter.
ExploreDuctwork & airflow
Free duct math that used to cost $400.
ExploreRefrigerant
R-410A, R-32, R-454B. All the math.
ExplorePro tools
For technicians and serious DIYers.
ExploreStart here
US climate zone map
Most of the sizing and rebate tools here ask for your climate zone. Look it up by ZIP once and the rest pre-fills from there.
Open the mapBefore you get a quote
How old is your HVAC unit?
Type the serial number off your furnace, AC, or heat pump and get the manufacture year. The age decides repair-or-replace.
Decode the serialBeyond the calculators
Answers, not just numbers.
Cost guides, brand matchups, and symptom-led repair help, each reviewed by a licensed pro.
Guides
One homeowner question per page, answered with numbers.
Troubleshooting
Start from the symptom, fix the cheap stuff first.
How everything here gets made.
Calculators, guides, comparisons, and troubleshooting alike come from ACCA Manual J, NEC Article 440, ASHRAE handbook tables, manufacturer engineering data, and the field experience of techs who do this work every day. Every page is reviewed by a licensed HVAC pro before it goes up.
Meet the reviewers01
Grounded in real practice
The calculators use the same inputs a contractor writes on a load sheet, and the guides and troubleshooting pages follow how a tech actually diagnoses and prices a job. Codes and engineering data, not guesswork.
02
Reviewed by working techs
Every tool and article credits its reviewer by name and trade certification, each one a licensed pro working the relevant trade. The full roster lives on the about page.
03
Written to be used
A number tells you what it means and what to verify; a guide tells you what to do next and when to call a pro. Useful on a service call, useful before you sign a quote.
Stop guessing. Start sizing.
Each sizing tool takes about 90 seconds and gives you a number you can show your contractor.