Pick your IMER tool and how far it sits from the outlet. Get the minimum extension-cord gauge to keep the motor fed with clean voltage — full power, no overheating.
Thin wire over distance bleeds off volts as heat. A motor starved of voltage can't make rated torque, so it bogs down and pulls even more current.
Low voltage means high amperage, and high amperage means heat. Sustained undervoltage cooks windings — the fastest way to burn up a good mixer or saw.
An undersized cord heats along its whole length — a fire and trip hazard. The right gauge keeps the cord cool, the breaker happy, and the tool performing.
Read down to your cord length, across to your tool's amp draw — the colored block is your minimum gauge. This is the reference the calculator above runs on.