Portable extension cord AWG from load, length, and drop limit

How to use this estimate

Enter the tool or device nameplate current in amps, the one-way length of the portable extension cord in feet, whether you are on 120 V or 240 V, and whether you want to keep voltage drop at or under 3% or 5%. CordAwg walks copper gauges from 16 AWG toward heavier sizes, skipping any gauge whose simple ampacity ceiling is below your load. For each candidate it estimates round-trip voltage drop with stranded copper DC resistance per thousand feet from a secondary NEC Chapter 9 Table 8 republication, then reports volts dropped, drop as a percent of supply, the first gauge that stays inside your limit, and approximate voltage remaining at the load. When that technical size is 16, 14, or 12 AWG and the corresponding shopping class ampacity covers the load, a VEVOR US deep link for that class can appear. If the math wants 10 AWG or heavier, or no 16–6 copper size fits the limit, you still see the independent numbers with an honest NO_MATCH on this three-step ladder — shorten the run, raise voltage, raise the drop allowance, or shop a heavier cord elsewhere rather than daisy-chaining thin cords. This screen is for temporary portable extension cords only. It is not a substitute for the National Electrical Code, a licensed electrician, or permanent branch-circuit design. Confirm outdoor or indoor rating, plug and receptacle ampacity, and that a thick cord with a 15 A plug is still a 15 A cord. CPSC guidance stresses avoiding overheating and treating extension cords as temporary, not as permanent wiring. Affiliate tracking is not active yet; comparison on this site is limited to the verified 16 / 14 / 12 AWG VEVOR US ladder shown here.