Use this calculator to determine the appropriate wire gauge for your automotive wiring needs based on length, amperage, and voltage.
Practical tips
Fuse it at the source: always protect the wire, not the device.
When in doubt go bigger: extra copper is cheap compared to a fried harness.
Stranded automotive‑grade copper (TXL/GXL or GPT): handles engine‑bay heat and vibration better than household THHN.
Battery cables and inverters (150 A +): jump straight to 2 AWG, 1/0, or welding cable.