New: SEER2 savings calculator now live
The HVAC tools contractors actually use.
Size your system, compare costs, plan ductwork, check refrigerant. Free tools built by licensed techs. No logins, no math by hand.
- Categories
- 6
- Built by techs
- Licensed
- Avg time per tool
- 90 sec
Most used
Start with the ones people open the most.
BTU sizer
The free BTU tool that asks about your insulation, ceilings, windows, and climate. Square-foot tools usually oversize you by 30%, and that costs you every month on your bill.
- Asks about your climate
- Factors in insulation
- Counts your windows
AC tonnage calculator
Right-size your air conditioner in tons.
Open tool Cost & ROIHVAC replacement cost
Installed price for AC, heat pump, or furnace.
Open toolDuct sizing calculator
Plan your ductwork in the browser. No PDFs, no expensive software.
Refrigerant charge calculator
Adjusts for your line-set length, unit capacity, and outdoor temperature.
Six categories
Every HVAC question, sorted.
From basic sizing for homeowners to refrigerant math for pros. Pick a category to see what is inside.
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.
ExploreWhy pros and homeowners trust us.
Real math against published codes. Every tool reviewed by a named, licensed technician with the credential listed at the top of the page.
01
Real questions, real answers
Our tools ask what actually matters. Your climate, your insulation, your window count. Not just "how big is the house?".
02
Checked by HVAC techs
Every formula is checked by working, licensed HVAC technicians. We cite our sources. No mystery math.
03
Built for real jobs
Results explain what the number means and what to do next, not just the answer in isolation. Designed for service calls and homeowner decisions, not textbook problems.
Stop guessing. Start sizing.
The BTU sizer takes 90 seconds and gives you a number you can show your contractor.