The Electrical Calculator Toolkit Built for the Field
Free professional calculators for voltage drop, cable sizing, conduit fill, Ohm's law and more. Built for electricians working to NEC, BS 7671, and AS/NZS standards.
Used by electricians across the UK, US, Australia & New Zealand
Free Electrical Calculators
Use these free tools in your browser - or download the Voltix app for the full toolkit of 12 calculators, offline access, and reference tables.
Voltage Drop
Check conductor voltage drop for any circuit. NEC, BS 7671 & AS/NZS.
Cable Sizing
Size cables to carry your load safely under BS 7671 & AS/NZS.
Wire Size
Find the right wire size for any NEC circuit by ampacity.
Conduit Fill
NEC Chapter 9 conduit fill - up to 40% for 3+ conductors.
Ohm's Law
Solve for voltage, current, resistance or power instantly.
Electrical Load
Calculate total panel load and check against your service size.
Wire Gauge
Look up ampacity, resistance, diameter and area for any AWG gauge.
Breaker Size
Size the correct overcurrent protective device for any circuit.
Cable Derating
Apply temperature and grouping factors to find derated ampacity.
Earthing / Grounding
Size protective earthing (BS 7671) and grounding (NEC) conductors.
Built for the Field
Dark mode, fast inputs, instant results - works offline on site.
The Full Toolkit in Your Pocket
The Voltix app gives you 12 professional calculators, offline access, and built-in reference tables - covering all three major electrical standards.
12 Professional Calculators
Every calculator a working electrician needs - from voltage drop to cable derating to earth fault loop impedance.
Works Offline
No signal on site? No problem. Every calculator works fully offline, no internet required.
Three Standards
Switch between NEC (US), BS 7671 (UK), and AS/NZS 3008 (AU/NZ) in one tap.
Reference Tables
Built-in cable ampacity tables, conduit fill charts, and correction factors - always at hand.
Free Core Calculators
Voltage drop and wire sizing are free forever. Pro subscription unlocks the full suite.
Privacy First
No account required. No data collected. Just calculations.
Built for Your Standard
One app, three wiring standards. Pick yours and Voltix adapts its formulas, tables and units to match.
Whether you're sizing conductors to NEC 310.16, checking conduit fill to Chapter 9, or running load calculations to Article 220, Voltix has you covered.
Wire Size · Conduit Fill · Electrical Load · Breaker Size · Grounding
Explore the NEC (US) referenceDownload Voltix Free on Android
All the calculators in your pocket. Free core tools, with a Pro subscription for the full suite. iOS coming soon.
Free to download. Pro features available by subscription.
Professional Electrical Calculators - Free Online and In the App
Voltix is a suite of professional electrical calculators built for working electricians, apprentices and electrical engineers. Every tool on this site is a real, functional calculator, not a demo, giving you instant, accurate results for the everyday calculations you face on site and in the office.
We support all three of the world's major wiring standards. In the United States that means the National Electrical Code (NEC), with conductor ampacity to Table 310.16, conduit fill to Chapter 9, and load calculations to Article 220. In the UK and Ireland we follow BS 7671:2018+A2:2022, the IET Wiring Regulations, for voltage drop, cable sizing and protective conductor sizing. In Australia and New Zealand we follow AS/NZS 3008.1 for cable selection and current-carrying capacity.
The web calculators are perfect for quick lookups at the desk or a fast check on your phone. For working on site - often without signal - the Voltix Android app gives you all 12 calculators completely offline, plus built-in reference tables for ampacity, conduit fill and correction factors. An iOS version is in development.
Start with the high-volume tools: voltage drop for any circuit, cable sizing under BS 7671 and AS/NZS, NEC wire sizing by ampacity, conduit fill to Chapter 9, and the universal Ohm's law calculator. Every calculator includes the underlying formula, a worked example, and answers to the questions electricians ask most.