Extension Cord Gauge Calculator
Enter your tool's amp rating and how long the cord needs to be, and see the thinnest wire gauge that can carry the load safely.
Use a cord of at least
12 AWG
A lower AWG number is a thicker wire, so any thicker cord (smaller number) is also fine.
Find the amp rating on the tool's label. If it only lists watts, divide watts by 120 (so a 1,500 W tool draws about 12.5 A). Always use a 3-conductor grounded cord, unroll it fully under load, and never chain two cords together.
Why length changes the answer
Longer cords lose more voltage, and a tool starved of voltage draws extra current and heats both itself and the cord. That is why the same saw needs a thicker cord at 100 ft than at 25 ft. Our extension cord gauge chart covers the full table and the cord rules worth following in a workshop.