Electrical Calculators

Working with electrical quantities

These calculators follow National Electrical Code tables and assume standard conditions: 75 °C terminations, no more than three current-carrying conductors in a raceway, and 30 °C ambient. Derating for temperature, bundling and continuous loads is not applied automatically, and local amendments vary.

Code-covered work must be designed and inspected by someone qualified to do it. Use these tools to check a design or size a run, not to replace an electrician.

These 9 calculators cover about 52,080 searches a month between them. Every one prints the formula it uses and a worked example, so you can check the result by hand before you order.