Wire Ampacity

Ampacity by gauge, conductor material, insulation rating, ambient.

Run the calculator

Example

You enter

AWG 12
Material copper
Insulation rating 75
Ambient temperature (°C) 30
Conductor bundle count 1

You get

Ampacity (physics estimate) 24.4 A

Details, formula, and sources

Ampacity selection from NEC 310.16 (0–2000 V), 75°C termination column by default; ambient correction per NEC 310.15(B)(1) and adjustment for >3 CCCs per NEC 310.15(C)(1).

NEC 2023 (NFPA 70).

Free read-only access at nfpa.org/freeaccess.

Estimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.

Field names used by the API: awg, material, insulation_rating_C, ambient_C, bundle_count, ampacity_A

Termination temperature 75°CNEC 110.14(C) default for the typical residential / light-commercial install
Ambient temperature 30°C unless user suppliesNEC 310.15(B)(1) base table
Current-carrying conductors per raceway ≤ 3 unless user suppliesNEC 310.15(C)(1) base case