Run the numbers.
Get the verdict.
Move on.
Code-accurate field calculators for HVAC and electrical that tell you what the reading means and what to do next, each cited to its NEC 2023 table or manufacturer PT data. Save a job and track it across visits. Free, offline, no login.
The yellow book behind the truck seat, reborn as an app.
Most used on the job
Superheat & Subcooling Calculator
Check refrigerant charge with PT interpolation for R-454B, R-32, R-410A, and 7 more. Four-quadrant diagnostics tell you what the numbers mean.
R-454B readyConduit Bending Calculator
Offsets, rolling offsets, 3- and 4-point saddles, stub-90s, back-to-back 90s, and kick-90s, with interactive bend diagrams and shrink tables.
7 bend typesVoltage Drop Calculator
Voltage drop for any run, plus reverse-solve for the minimum wire size that meets NEC recommendations. Tells you if the run passes or needs a bigger conductor.
NEC 2023EV Charger Install Calculator
Wire, breaker, and panel sizing for Level 2 charger installs per NEC 625, with GFCI requirements and a parts list. Flags whether your panel can carry it.
NEC 625More calculators
Wire Size Calculator
NEC 310.16 ampacity with temp derating and bundling.
Conduit Fill Calculator
NEC Chapter 9 fill for EMT, IMC, RMC, PVC, and ENT.
Box Fill Calculator
Junction box fill per NEC 314.16.
BTU Load Calculator
Cooling and heating load by climate zone, room-by-room.
Wire Size for Appliances
Breaker and wire for a dryer, range, water heater, hot tub, AC, pump, and more, from the NEC tables.
What Size AC Do I Need?
AC size by room or whole house from the ENERGY STAR table and climate zone, with tonnage.
Built for the field, not the office.
Every calculator shows the math and cites its source: NEC table numbers, refrigerant PT data, manufacturer specs. Open it at the panel or the condenser and get your answer, and what to do about it, in seconds.
No login. No paywall. No spam.