Copper vs Aluminum Wire Size
Common copper-to-aluminum substitutions that should still be checked for terminals, derating and voltage drop.
- Source
- NEC ampacity table
- Edition
- 2023
- Updated
- 2026-07-27
- Scope
- United States
Lookup Table
How much larger does aluminum need to be than copper?
| Copper | Nearest aluminum starting point | Check |
|---|---|---|
| 12 AWG | 10 AWG | Small-conductor limits bind |
| 8 AWG | 6 AWG | Confirm terminations |
| 6 AWG | 4 AWG | Confirm derating and lugs |
| 3 AWG | 1 AWG | Feeder-size range |
| 1/0 | 3/0 | Voltage drop may govern |
Calculated against the NEC 2023 edition using 310.16, 110.14(C). Confirm the edition adopted by your AHJ, which may differ and may carry local amendments.
Not covered by this tool
- Local amendments and equipment markings can be stricter than this reference view.
- Marginal values should be checked directly against the adopted edition.
- This page is a routing aid and does not replace the owning calculator for project-specific inputs.
Data last verified