HVAC Calculators
Free HVAC Calculators
Load sizing with climate-zone-adjusted BTU calculations and refrigerant diagnostics with full pressure-temperature interpolation. Built for HVAC contractors and technicians.
BTU / HVAC Load Calculator
Calculate cooling and heating load by climate zone, insulation, windows, and duct location. Whole-house or room-by-room breakdown with automatic tonnage sizing.
A2L supportSuperheat & Subcooling Calculator
Check charge level with PT interpolation for 10 refrigerants including R-454B and R-32. Four-quadrant diagnostic decision tree with TXV and fixed orifice targets.
Frequently Asked Questions
Are these HVAC calculators free?
Yes. Every calculator is completely free — no login, no email gate, no ads. We build these tools because they help trade contractors do better work. Intry Systems makes money from our AI dispatch product, not from calculators.
How accurate is the BTU calculator?
The BTU calculator uses ACCA Manual J simplified methodology with ASHRAE-referenced base values and IECC climate zones. It is an estimate for planning purposes — not a substitute for a professional Manual J calculation required for permits and equipment selection. Results are typically within 15-20% of a detailed Manual J.
Which refrigerants does the superheat calculator support?
The calculator includes R-410A, R-407C (with zeotropic glide handling), R-134a, R-404A, R-22 (legacy), R-454B (Puron Advance), R-32, R-448A, R-449A, and R-290 (propane). PT tables are sourced from Carrier/Copeland charts and cross-referenced with Sporlan tables.
Need more than calculators?
Emily diagnoses HVAC jobs over SMS — system replacements, no-cool calls, maintenance visits — and builds structured dispatch briefs before your tech rolls.