What gauge extension cord should I use for heavy outdoor use?

Skip 14 AWG for heavy outdoor use — it’s too thin and will drop voltage and overheat with tools pulling 12–15 amps over 50+ feet. For most outdoor jobs, use at least 12 AWG, which handles 15 amps up to 100 feet. For 20-amp tools like big air compressors or welders, jump to 10 AWG.