Enter the load's amps or watts and the cord length to check whether a common gauge is safe or whether you need something heavier.
Longer cords derate current capacity due to voltage drop and heat buildup — this checks against standard household extension cord ampacity tables.
A 14 AWG cord that's safe for 15A at 25 feet isn't necessarily safe at 100 feet — voltage drop and heat both increase with length, so longer cords need a heavier gauge for the same load. This is especially relevant for generator or off-grid setups where cords run further than a typical household extension.
The gap between what a cord is rated for and what's actually safe over distance catches a lot of people off guard, especially with generators — a cord that's perfectly fine for a 25-foot run in a garage can be genuinely unsafe at 100 feet for the same load, which is exactly the scenario a generator setup often creates.
Many portable generators ship with basic 16 AWG cords rated for light loads only — for anything over 1500W or runs past 50 feet, stepping up to 12 or 10 AWG is safer.
Yes, but the combined length increases voltage drop and the weakest (thinnest) segment sets the safe limit for the whole run — treat the total length as one cord when checking gauge.
Both interact — gauge sets the baseline capacity and length reduces it further through voltage drop and heat buildup, so the safe amperage for any given cord is really a function of both together, not either one alone.