Fieldwatt Electrician NEC Calc

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

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