Built for the field · Works offline
BTU load, duct sizing, NEC voltage drop & wire size, refrigerant P-T charts, superheat & subcooling — on your phone, in the attic, with every formula cited. ASHRAE. NEC 310.16. SMACNA. No ads, no tracking.
ASHRAE
friction-rate duct equation
NEC 310.16
exact ampacity tables
SMACNA
duct construction standards
CoolProp
refrigerant saturation data
Free calculators · right here in the browser
Three of the app's calculators run on this site, free: thesuperheat & subcooling calculatorfor R-410A, R-454B, R-32 and R-22, aduct size calculatorthat works like a ductulator, and aCFM calculatorfor tonnage, temperature rise and air changes. Same formulas, same sources, no sign-up.
Gauge pressure and line temperature in, superheat or subcooling out, with a verdict against the target. R-410A, R-454B, R-32, R-22. Target superheat for fixed-orifice systems too.
Open the calculator →Free · runs in your browserRound or rectangular duct size for any airflow and friction rate, with the velocity check that tells you if it will be noisy.
Open the calculator →Free · runs in your browserAirflow from tonnage, from furnace temperature rise, or from room air changes — the three ways techs actually need CFM.
Open the calculator →Calculator features · check current app access
Duct sizing is listed as a Pro feature. See the App Store and in-app offer for current access, plans and eligibility.
Heat and cool sizing from square footage, ceiling height, climate zone, occupancy, and sun exposure. ASHRAE-derived rules of thumb.
ASHRAE friction-rate equation, Manual D simplified. Round and rectangular, equivalent-diameter solver, velocity check with noise warnings.
Every unit the trade touches — BTU, kW, tons, CFM, L/s, °F/°C, psi, kPa, in wc. Imperial default, metric one tap away.
PlateScan · Pro
Point the camera at the unit's data plate — or just type the model number. PlateScan decodes nominal tonnage and refrigerant from the manufacturer's model nomenclature (Trane, Goodman, York, Rheem, Lennox, Carrier and family) and autofills the right calculator. Fully offline. You confirm every value before it's used — it's a typing-saver, not a guess.
More app features · check the current in-app offer
NEC voltage-drop method tied to exact NEC Table 310.16 ampacity — not approximations. 3%/5% checks built in.
R-410A, R-32, R-454B, R-22. CoolProp-backed saturation data with bubble/dew handling for blends.
Enter pressures and line temps, get charge diagnostics with the target ranges for TXV and fixed-orifice systems.
Point the camera at the data plate — or type the model — and it decodes tonnage and refrigerant, then autofills the right calculator. Offline.
Name and save a calculation. The app attempts private iCloud sync when available; check the job on your other device before relying on it.
Job name, inputs, result, and the standard cited for the formula — ready to hand to a customer or attach to a submittal.
01
BTU load, duct, voltage drop, P-T, superheat — the grid is one screen, gloves-friendly.
02
Pressures, line temps, square footage, run length. Every input has its unit right there.
03
"BTU load: 28,800. Source: ACCA Manual J Simplified." The formula's standard is printed under every result.
Field guides
The calcs behind the calculators — superheat, PT charts, duct sizing, NEC wire sizing — written the way a senior tech would explain them.
The formula, where to clamp, and target ranges for fixed-orifice and TXV systems.
Read the guide →RefrigerantFull pressure-temperature table with bubble and dew columns, plus how glide changes your readings.
Read the guide →Airflow & Ducts400 CFM/ton standard air — when to run 350 in humid climates and 450 in dry ones.
Read the guide →Airflow & DuctsTrunk and return sizes at 1,200 CFM, round-to-rectangular equivalents, and velocity limits.
Read the guide →ElectricalSize off the nameplate MCA — not tonnage — with NEC 310.16 and 10/2 vs 10/3 explained.
Read the guide →ElectricalMOCP vs MCA off the nameplate, typical 30–45A range, and the oversized-breaker red flag.
Read the guide →Duct sizing is listed as a Pro feature. See the App Store and in-app offer for current access, plans and eligibility.
