🧰 Field calculators · free, no sign-up
Free Field Calculators for the Trades
The calculations you run on the job, built on the real code tables — NEC 310.16 ampacity, Chapter 9 conduit fill, 314.16 box fill, SMACNA/ASHRAE duct velocities, IPC fixture units, and pipefitting trig. Every result cites the governing table. Free in your browser, no account needed.
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Wire Size Calculator — NEC 310.16
NEC 310.16 ampacity + 240.4(D) caps + voltage-drop upsize
⚡ Electrical→
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Conduit Fill Calculator — NEC Chapter 9
THHN/THWN at 40% fill — NEC Ch.9 Tables 1, 4 & 5
⚡ Electrical→
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Box Fill Calculator — NEC 314.16
NEC 314.16(B) allowances + standard box suggestion
⚡ Electrical→
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Duct Size Calculator — SMACNA / ASHRAE Velocity Method
CFM → spiral & rectangular sizes by allowed noise (NC)
🌀 HVAC / Sheet Metal→
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Pipe & Drain Size Calculator — IPC Fixture Units
WSFU / DFU fixture-unit sizing + hydronic velocity
🔧 Plumbing→
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Rolling Offset Calculator — Pipefitting Trig
Travel, run & true offset for 22.5/30/45/60° fittings
🔩 Pipefitting→
Learn the code behind the calculator
Every one of these tools reads straight from a code table — and CraftIQ teaches those same tables through 1,069 real-jobsite puzzles. Browse the sections in the code reference library, or start practicing your trade: electrical, plumbing, HVAC, or pipefitting.