NEC Electrician Calc: VoltKit

The electrician's calculator that works where you do - in the basement, in the panel, in the dead zone.

VoltKit is a fast, no-nonsense field calculator for electricians, apprentices, estimators, and inspectors. Six pro calculators, grounded in the National Electrical Code (NFPA 70), all running 100% on your phone. No account. No login. No internet. Just answers.

FULLY OFFLINE - ALWAYS
Crawlspaces, mechanical rooms, new construction with no service yet - VoltKit needs zero signal. Every table, every formula, every result is computed on-device. Drop into a concrete basement and it works exactly the same as it does on the roof. Your data never leaves your phone because there's nothing to send.

NEC-GROUNDED, NOT GUESSED
The numbers come straight from the code book - ampacity from Table 310.16, the 240.4(D) small-conductor rules, conduit and conductor areas from Chapter 9, box-fill volumes from 314.16(B), and EMT take-up for stub-ups. Real values, not approximations. (Estimation aid only - always verify against the current NEC and your local AHJ.)

SIX PRO CALCULATORS
- Voltage Drop: any AWG/kcmil. Volts dropped, % drop, voltage at the load, a pass/fail on the 3% / 5% recommendations, and the smallest wire size that keeps you in spec.
- Wire Size & Ampacity: the 60/75/90C ampacity for any conductor, the 240.4(D) overcurrent cap, and the minimum wire size for a load.
- Conduit Fill: EMT, RMC, IMC, PVC 40/80, ENT; add your conductors and get the minimum trade size plus fill % at every size against the 53% / 31% / 40% limits.
- Box Fill: conductors, clamps, device yokes, support fittings and grounds; required cubic inches and a fit check against your box's marked volume.
- Ohm's Law: enter any two of volts, amps, ohms, watts and solve the other two.
- Conduit Bending: offsets (distance between bends + shrink), 90-degree stub-ups (first-bend mark from take-up), and three-point saddles.

FREE FOREVER
All six calculators, unlimited use, on single-phase copper - no trial, no ads, no sign-in. Conduit fill, box fill, Ohm's law and bending are complete and unrestricted. Plus up to three saved jobs.

ONE-TIME PRO. NO SUBSCRIPTION. EVER.
Unlock VoltKit Pro once for $9.99 and keep it:
- Three-phase: voltage drop and wire sizing on commercial and industrial circuits.
- Aluminum conductors: feeders and service entrance, sized against the 310.16 aluminum columns.
- Unlimited