Wire Size by Run Distance

Pick your one-way distance for the full gauge × amperage breakdown. Reference sizes shown at 240 V copper, 3% drop.

Distance	@ 20 A (240 V)	@ 50 A (240 V)	@ 20 A (120 V)
50 ft	14 AWG	8 AWG	10 AWG
100 ft	10 AWG	6 AWG	8 AWG
150 ft	8 AWG	4 AWG	6 AWG
200 ft	8 AWG	4 AWG	4 AWG
250 ft	6 AWG	3 AWG	4 AWG
300 ft	6 AWG	2 AWG	3 AWG
400 ft	4 AWG	1 AWG	2 AWG
500 ft	4 AWG	1/0 AWG	1 AWG

Built & maintained by Murugan Vellaichamy · Every calculation verified against NEC Chapter 9 Table 8 & Table 310.16 published values · Informational reference — not engineering advice