Use 12-gauge for a 100-foot extension cord with a 15-amp saw.

Yes, you need 12-gauge. 14-gauge will technically handle 15 amps, but over 100 feet the voltage drop kills your saw’s power and can overheat the cord. The saw will bog down, the breaker might trip, and you risk damaging the motor.

Don’t cheap out. A 14-gauge cord is fine for a 50-foot run with a light drill, but 100 feet changes things. The extra resistance means the saw pulls more current to compensate, which heats up the wire and wastes energy. With 12-gauge you keep voltage closer to 120V, the saw runs full power, and the cord stays cool.

Check the cord’s rating—it should say “12/3” (12-gauge, three conductor). Also make sure it’s rated for outdoor use if you’re working outside. A good 100-foot 12-gauge cord is heavy and costs more than you want, but it’s way cheaper than a new saw.