Free NEC 2023 Electrical Calculators
These run in your browser on the same engine as the Voltkit app, grouped the way the app groups them. Values checked against the printed NEC 2023 tables, and every result names the section it comes from.
Wire & Conduit
Conductor size, voltage drop, and whether it all fits in the pipe and the box.
- NEC Ch. 9
Conduit Fill
Mixed wire sizes with per-wire insulation in any of 10 raceways, plus the 60% nipple rule. - NEC 210.19(A)
Voltage Drop
Single- or three-phase drop by the approximate-K or the exact Table 9 impedance method. - NEC 310.16 · 110.14(C)
Wire Size
The smallest conductor that meets both ampacity (with terminal limits) and voltage drop. - NEC 314.16
Box Fill
Itemized 314.16(B) allowances against any of the 24 standard boxes or your own volume. - NEC 314.28
Pull Box
Minimum box length for straight, angle and U pulls, and spacing between raceway entries.
Also in the app Wire Ampacity · Parallel Sets
Bending
Marks, multipliers and shrink for hand-bent EMT and rigid. Bend geometry, not NEC.
Also in the app Bend Length · Segment Bend · Bend Total · Concentric
Power & Fundamentals
Everyday electrical math and transformer protection.
In the app Ohm's Law · AC Power · Transformer · Power Factor
Service & Grounding
EGC and GEC sizing, including the 250.122(B) upsize after you go up for voltage drop.
Also in the app Dwelling Load · Appliance Demand
Motors
Article 430 motor circuits and feeders.
In the app Motor · Motor Feeder
All 21 calculators work offline in the Voltkit app for iPhone and Android.