Fieldwatt: NEC Calculators

Ryabinski Labs

About this app

Five NEC electrical calculators built for the field — fast, offline, and made for working electricians. Stop fumbling with paper tables and clunky web pages on a ladder. Fieldwatt gives you the answers you need, right when you need them.

VOLTAGE DROP CALCULATOR
Size conductors with confidence. Enter voltage, current, distance, wire size and material — get voltage drop and percentage instantly. Check single-phase and three-phase runs, copper or aluminum, and know whether you're inside the 3%/5% recommended limits before you pull a single foot of wire.

CONDUIT FILL CALCULATOR
Never over-stuff a pipe again. Pick your conduit type and size, add your conductors, and Fieldwatt shows fill percentage against NEC Chapter 9 limits (40%, 31%, 53%). Mixed wire sizes, multiple conductors — handled.

CONDUIT BENDING CALCULATOR
Bend it right the first time. Offsets, saddles, 90s, and stub-ups with the exact take-up, shrink, and multiplier math worked out for you. Less scrap, fewer re-bends, cleaner runs.

BOX FILL CALCULATOR
Stay compliant on every junction and device box. Count conductors, devices, clamps, and grounds — get required cubic inches per NEC 314.16 and instantly see if your box is legal.

WIRE AMPACITY CALCULATOR
Look up conductor ampacity in seconds. Account for insulation temperature rating, ambient temperature, and conductor bundling derates so you size wire safely and to code.

WORKS OFFLINE — ANYWHERE YOU WORK
Mechanical rooms, basements, new construction, rural sites — no signal, no problem. Every calculator runs fully offline. No spinner, no "no connection" error, just answers.

BUILT FOR THE TRADE
Dark, high-contrast "field-instrument" interface — amber readouts on charcoal — that's easy to read in a dim panel room or bright sunlight. Big tap targets for gloved hands. Monospace digital displays you can read at a glance.

FREE TO START
All five calculators are free. No trial timer, no paywall on the math. Download it, use it on the job today.

GO PRO ($9.99/mo or $99/yr)
Upgrade when you're ready to work faster:
• Saved jobs — store calculations per job/site and sync them across your devices
• Material lists — turn your calcs into pull sheets and takeoffs
• Code-reference updates — stay current as tables and code cycles update

WHO IT'S FOR
Licensed electricians, apprentices studying for the journeyman or master exam, estimators, inspectors, and electrical contractors who want NEC math that's quick, correct, and always in their pocket.

Download Fieldwatt and put five code calculators in one app.

Privacy: fieldwatt.app/privacy