Voltbox: Electrician Toolkit

Fast NEC calculators for electricians. One-time purchase, never a subscription.

Voltbox is a professional calculator toolkit for electricians, built around the NEC (National Electrical Code). Fast, accurate, and yours to own — pay once, keep it forever.

CALCULATORS INCLUDED • Ohm's Law — voltage, current, resistance, power, series/parallel • Wire & Cable Sizing — NEC ampacity lookup • Conduit Fill — max conductors per conduit size, including bare wire • Box Fill — junction box conductor capacity • Voltage Drop — for any run length and load • Motor FLA / Transformer Sizing — full-load amps per NEC 430

WHY VOLTBOX • One-time purchase for Pro — never a subscription, never a recurring fee • Save and organize calculations by project • Built for the job site: fast, no clutter, no login screens, works with no signal • No account required — open the app and start calculating

Ohm's Law and Wire Sizing are free. Unlock Pro once to get Conduit Fill, Box Fill, Voltage Drop, and Motor/Transformer sizing — forever.

Voltbox is a reference tool based on the NEC. Always verify results against the current code edition adopted in your area and confirm compliance with a licensed electrician or your local inspector before performing any installation.