Fieldwatt Electrician NEC Calc

Ryabinski Labs

About this app

Five NEC calculators for electricians in one offline app — voltage drop, conduit fill, conduit bending, box fill, and wire size / ampacity. Free to use.

No signal in the mechanical room, the basement, or a rural panel? Fieldwatt runs 100% offline. Once it's loaded, every calculation works with zero bars — no login, no waiting, no paywall on the math.

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FIVE CALCULATORS, ONE APP
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⚡ VOLTAGE DROP
Size a run and check % drop in seconds. Copper or aluminum, single- or three-phase. Based on NEC Chapter 9, Table 8.

⚡ CONDUIT FILL
Drop in your conductors and get fill % instantly. All common conduit types and wire sizes, per NEC Chapter 9, Tables 1, 4 & 5.

⚡ CONDUIT BENDING
Offsets, saddles, and 90° stubs without the head-math. Get your marks fast and bend it right the first time.

⚡ BOX FILL
Count conductors, devices, clamps, and grounds and stay legal under NEC 314.16.

⚡ WIRE SIZE & AMPACITY
Look up conductor ampacity and size by insulation temperature rating and conditions, straight from NEC Table 310.16.

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BUILT FOR THE TRADE
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• Dark "field-instrument" UI — amber on charcoal, easy to read in a dim panel room or bright sun
• Big tap targets that work with gloves on
• Live results that recompute as you type
• Every answer cites the NEC table or section behind it
• NEC 2023 reference values

Whether you're pulling wire, bending pipe, filling boxes, or studying for your journeyman or master exam — the numbers you reach for most, in one fast app.

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FREE TO START
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All five calculators are free. No trial timer. No paywall on the math. Install it and use it on today's job.

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GO PRO
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Upgrade to Fieldwatt Pro when you want to save the work:

• Saved jobs that sync across your phone, tablet, and the web
• Material lists, pull sheets & takeoffs built from your calculations
• Code-reference updates

Pro is $9.99/month or $99/year. The calculators stay free either way.

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WHO IT'S FOR
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Licensed electricians, apprentices, estimators, inspectors, and electrical contractors who need NEC-accurate answers fast — on the job and off the grid.

Web app and blog: fieldwatt.app
Privacy: fieldwatt.app/privacy

Keywords: electrician calculator, electrical calculator, voltage drop calculator, conduit fill calculator, conduit bending calculator, box fill calculator, wire size calculator, wire ampacity, NEC calculator, NEC 2023, electrician app, electrician tools, journeyman exam, apprentice, offline electrical calc.