14-gauge vs 16-gauge extension cord for lawn mower: 14-gauge is the minimum safe choice

16-gauge is too thin for a lawn mower—electric mowers draw enough current that thin wire causes voltage drop, preventing startup or causing overheating. 14-gauge handles most residential mowers up to 100 feet; step up to 12-gauge for runs over 150 feet or heavy-duty models. The thicker cord costs $5-10 more but avoids fire risk or a dead mower.