About Voltix

Voltix is a toolkit of professional electrical calculators built for the people who actually wire buildings — electricians, apprentices, inspectors, and electrical engineers. Our goal is simple: give you fast, accurate answers to the calculations you do every day, whether you're at the desk or on site with no signal.

Every calculator on this site is a real, working tool built against the actual published standards — not an approximation or a rule of thumb dressed up as a calculator. We show the formula behind every result so you can check our working and understand exactly what the calculation is doing.

Built for three standards

Electrical work doesn't follow one rulebook. The three major standards used across the English-speaking world have different voltage systems, different cable sizing methodologies, different earthing philosophies, and different ampacity tables. Voltix supports all three:

• NEC — the National Electrical Code, used across the United States and adopted by reference in many US territories. Covers AWG conductor sizing, NEC Table 310.16 ampacity, Article 220 load calculations, Article 430 motor circuits, and Chapter 9 conduit fill. See our NEC reference guide.
• BS 7671 — the IET Wiring Regulations (18th Edition), used throughout the UK and Ireland and referenced by many other jurisdictions. Covers metric cable sizing, BS 7671 correction factors (Ca, Cg, Ci), the adiabatic equation for earth sizing, and disconnection time requirements. See our BS 7671 reference guide.
• AS/NZS— the Australian and New Zealand Wiring Rules (AS/NZS 3000:2018) and cable selection standard (AS/NZS 3008.1). Shares the same 230 V / 50 Hz supply as BS 7671 but has its own correction factor tables and RCD requirements. See our AS/NZS reference guide.

The calculators

Voltix currently offers ten free calculators covering the most common calculations electricians perform daily:

• Voltage drop calculator — NEC, BS 7671 and AS/NZS, for single-phase and three-phase circuits
• Cable sizing calculator — BS 7671 and AS/NZS ampacity-based sizing with full derating
• Wire size calculator (NEC) — NEC Table 310.16 ampacity lookup by current draw
• Conduit fill calculator — NEC Chapter 9 fill percentage for any conduit type and wire mix
• Ohm's law calculator — voltage, current, resistance, and power from any two values
• Electrical load calculator — NEC Article 220 demand load and service size for residential panels
• Wire gauge calculator (AWG) — full specifications for any AWG size: diameter, resistance, and ampacity
• Circuit breaker size calculator — NEC OCPD sizing for general, continuous, and motor loads
• Cable derating calculator — BS 7671 and AS/NZS correction factors (Ca, Cg, Ci)
• Earthing and grounding calculator — CPC sizing under BS 7671 and EGC sizing under NEC Table 250.122

Accuracy and our approach

Every calculator is verified against the current edition of the relevant standard before publication. Where a standard provides lookup tables (NEC Table 310.16, BS 7671 Appendix 4, NEC Chapter 9 Table 5), we use the actual table values — not interpolated approximations. Where a standard provides a formula (the adiabatic equation, the NEC voltage drop formula, the BS 7671 mV/A/m method), we implement the formula exactly and show it alongside the result.

We also show worked examples for every calculator so you can confirm that Voltix's output matches what you'd get by hand. If you find a discrepancy, we want to know — accuracy is the point.

That said, these calculators are a professional aid, not a substitute for engineering judgment. Standards are updated periodically, local amendments may apply in your jurisdiction, and installation-specific factors (soil thermal resistivity, actual ambient temperatures, specific equipment ratings) can all affect the correct answer. Always verify results against the current edition of your wiring standard and the specific conditions of the installation.

The Voltix app

The web calculators on this site are ideal for quick checks at the desk. The Voltix app takes the same calculation engine offline. On a job site with no internet, the app still works — all ten calculators, all three standards, all reference tables. No account required, no sign-up, no data collection.

The app also includes the full reference tables you'd otherwise look up in the back of the standards: NEC Table 310.16 in full, BS 7671 Appendix 4 current-carrying capacity tables, conduit area tables, and the correction factor tables for temperature and grouping. Having these in your pocket on site means one fewer book to carry.

The blog

The Voltix blog covers the theory behind the calculations — not as abstract physics, but as practical knowledge that makes you a better electrician. Articles cover topics like voltage drop in practice, cable derating factors, RCD requirements under BS 7671, NEC motor circuit protection, and more. New articles are added regularly covering all three standards.