What is AWG current capacity?

It is the maximum current, in amps, that a conductor of a given American Wire Gauge size can carry continuously without exceeding its insulation temperature rating. Values here follow the standard NEC Table 310.16 base ampacity for up to three current-carrying conductors at 30C ambient.

Why does the insulation temperature rating change the ampacity?

Higher-temperature insulation (90C, such as THHN) tolerates more heat before breaking down, so the same copper or aluminum conductor is allowed to carry more current. The termination at a breaker or device may still limit you to the 60C or 75C column, so check the equipment rating too.

Why is aluminum ampacity lower than copper at the same gauge?

Aluminum has higher electrical resistance than copper, so it produces more heat per amp of current. To stay within the same insulation temperature limit, aluminum conductors are rated for less current than copper at an identical AWG size.

Do these values need any adjustment for a real installation?

These are base table values at 30C ambient with no more than three current-carrying conductors bundled together. More conductors in one conduit, higher ambient temperature, or long cable runs with voltage drop can all require a lower working ampacity than the base table shows.

What is the smallest AWG size available for aluminum wire?

12 AWG is the smallest standard aluminum branch circuit conductor size in the NEC table. Aluminum is not commonly used at 14 AWG, so this tool only lists 12 AWG and larger for aluminum.

AWG Current Capacity

Name: AWG Current Capacity
Availability: InStock
Author: Nham Vu

Pick a wire material, AWG size, and insulation temperature rating to read the safe ampacity from the standard NEC table.

Wire Specification

Conductor Material

AWG Size

Insulation Temperature Rating

Ampacity

amps

Based on NEC Table 310.16 base ampacity at 30C ambient with no more than three current-carrying conductors. Higher ambient temperature, more bundled conductors, or long runs can lower the real working ampacity below these values.

Full Reference Table — Copper

AWG	60C	75C	90C

Summary

Pick a wire material, AWG size, and insulation temperature rating to read the safe ampacity from the standard NEC table.

How it works

Select the conductor material: copper or aluminum.
Choose the AWG wire size from the dropdown.
Select the insulation temperature rating: 60C, 75C, or 90C.
Read the ampacity result and see it highlighted in the full reference table below.

Use cases

Check whether an existing wire gauge supports a new appliance load.
Confirm a wire size matches the breaker rating before wiring a circuit.
Compare copper and aluminum ampacity for the same gauge.
Look up the effect of insulation temperature rating on a wire's rated current.
Cross-check a wire spec sheet against the standard ampacity table.

Frequently Asked Questions

Last updated: 2026-07-21 · Reviewed by Nham Vu