HVAC Calculators
Free calculators and field references for HVAC technicians and mechanical engineers. Size loads, check refrigerant charge, size glycol systems, look up PT data — no signup, works on mobile.
Calculators
5
References
2
Refrigerants covered
7
Climate zones
8
Calculators
References
Tip
Every calculator supports imperial and metric units, shows a worked
example, and links to the relevant reference data. Results are a
scoping estimate — always verify against manufacturer charging charts
and current code before installed work.
No LTE on the roof, none in the crawlspace
The web page won't load where you charge the unit
HVAC Toolkit keeps R-410A/R-454B PT curves on the phone, logs each check, and exports the run for the ticket. No signal, no login. Pay once.
CalcSpec tools are estimators for qualified technicians and engineers. Results do not replace manufacturer charging charts, ACCA Manual J, AHRI-certified instruments, or the judgment of a licensed HVAC contractor.