This page covers one aspect of conductor work. For the complete free tool (ampacity, voltage drop, conduit fill, and derating together), use our conductor sizing calculator.

Conductor ampacity calculator

Size conductors with a wire ampacity calculator that applies Code table logic, temperature correction, and bundling derating. Built for feeders and branch circuits where documentation matters.

Related: full conductor sizing calculator, ampacity and derating guide, Voltage drop calculator.

How this calculator works

Select conductor size, material, insulation, ambient temperature, and installation details. The app applies derating steps and reports the resulting ampacity you can compare to load current.

Code alignment

The workflow reflects adopted electrical code ampacity practice. Verify table editions, corrections, and any local amendments that apply to your installation.

Ampacity in context

For most jobs, use the unified conductor sizing calculator so ampacity and voltage drop are checked on the same run.

FAQ

How is conductor ampacity determined in professional work?

Ampacity depends on conductor material, insulation temperature rating, ambient conditions, and derating for bundling or other installation factors. A calculator keeps the adjustments organized so the final size matches code tables and project inputs.

Does the tool apply temperature correction and bundling derating?

Yes. You can enter the conditions that affect ampacity so the result reflects common derating scenarios instead of table values alone.

When should I use ampacity-only versus ampacity plus voltage drop?

Use ampacity-only when thermal limits are the primary question. Use the combined tool when you also need maximum length or drop limits on the same run.