About WhatSizeWire

WhatSizeWire exists because the NEC tables you need for one job are spread across several chapters and are hard to read on a phone at the panel. Each calculator applies one table or formula, shows the numbers it used, and links the rule behind it, so an electrician, an inspector or a careful homeowner can check the result rather than take it on faith.

Who runs WhatSizeWire

WhatSizeWire is written and maintained by Hassan Nawaz (B.Sc. Electrical Engineering).

How the numbers are checked

The calculators follow the conductor properties and fill rules in the National Electrical Code (NEC) chapter 9 tables and article 310 ampacity tables, plus standard power formulas. Every tool runs in your browser, and each page shows its formula so you can check the math yourself. Before publishing, every calculator is tested against worked examples. When a source changes or a reader reports a problem, the page is checked again.

Limits

Electrical results are estimates for planning. Follow the code adopted where you live, and have a licensed electrician check any work that affects safety.

Corrections

If a figure looks wrong, please contact us with the page and the value. Confirmed errors are fixed quickly.