About Cable Size Calculator

Free wire and cable sizing calculator for DC, single-phase, and three-phase AC circuits. Covers AWG 14 through 4/0 copper and aluminum, ampacity per NEC 310, and voltage-drop limits — with a full AWG reference table.

Cable Size Calculator is an independent resource focused on electrical cable sizing, wire ampacity, and voltage drop for NEC-compliant wiring. We publish practical, carefully researched guides for readers who want clear answers without the fluff — whether you are just getting started or looking to sharpen what you already know.

What we do

Every article is written and edited to be genuinely useful: accurate, easy to follow, and grounded in real-world experience. We cover topics across Guides and update our guides as best practices evolve. We are not affiliated with any of the brands, products, or organizations we may reference; mentions are for the reader's benefit, not an endorsement.

How we stay free

Cable Size Calculator is supported by advertising. We display ads (including ads served by third parties such as Google AdSense) so that our content can remain free to read. Advertising never dictates our editorial recommendations. See our Privacy Policy for details on how ads and analytics work on this site.

Editorial standards & disclaimer

Cable Size Calculator is an independent reference tool and is not affiliated with, endorsed by, or sponsored by NFPA, NEC, or any manufacturer. Results are estimates only — always verify against the current National Electrical Code and consult a licensed electrician before installation.

Our content is provided for general informational purposes only and does not constitute professional advice. Always use your own judgment and consult a qualified professional where appropriate.

Get in touch

Questions, corrections, or feedback are always welcome. Reach us at runbookify@gmail.com or visit our contact page.