How To Tell What Gauge Wire Is: Learn Different Methods to Calculate It

The gauge of the wire tells how much electrical current a wire can carry without heating up.

Suppose you accidentally pass a current higher than a particular wire gauge’s rated current carrying capacity.

The electrical wiring may heat up and generate heat leading to wire deterioration. It may further affect its insulation which may cause an electrical fire.

Then, how to tell what gauge wire is?

There are two ways. Let’s get into the details of both methods.

With a Wire Stripper:

Recently, electricians have been using cable colors to know the polarity of the wire (whether neutral or hot).

The wire insulation indicates the American Wire Gauge sizes of the wires. 

However, if something is wrong with the indications, you should look for a wire stripper.

Step 1: Expose the wire

First of all, shut the power off at the electrical circuits. Ensure the power is off by turning on the light, checking the plug with the plug-in appliance, or using a voltage tester. 

Remove the cover or the faceplate from the electrical box.

You will see multiple wires inside attached to a light socket, switch, plug, or electrical connector.

Use screwdrivers to loosen the connector and take the wires apart.

Don’t touch the wire with your bare hands. Use long nose pliers with insulated handles to hold the wires.

Step 2: Determine the wire size:

You can use a wire stripper to determine the wire’s diameter or AWG size.

As wire strippers have round holes with AWG sizes mentioned over them, you can quickly determine the diameter by inserting the wires in their corresponding holes.

Once you know the wire diameter, you can refer to the AWG wire gauge chart and list the wires according to their AWG size.

wire strippers

Caption: wire strippers

How To Tell What Gauge Wire Is: By Measuring Cross-section

If you don’t own a wire stripper, you can calculate by measuring the cross-section of the wire.

Step 1:

Firstly, observe the electrical cable insulation. Look for any text written on the cable.

The last number written on the cable indicates the AWG of the wire.

If no text is written, jump to the next step.

Step 2:

Cut the wire perpendicular to its run with the help of wire cutters.

Step 3:

Now, measure the diameter of the wire’s cross-section.

Don’t add wire insulation while measuring the diameter.

Step 4:

Now, divide this wire diameter by .46. Calculate the logarithm of this result with the help of the “log” button on the calculator.

Now, divide this logarithm value by -.050305. Subtract three from the resulting value. The final value is the AWG of the wire.

voltage tester

Caption: voltage tester


Determining wire gauges requires minimal equipment, which works virtually for all wires and cables.

The cables are the main functional component of any electrical device.

Always look for high quality and the right gauge.

Cloom is the world’s leading manufacturer of top-quality wiring harnesses and customized cable assemblies, which you get after the toughest quality assurance tests.

Hey, I am John, General manager of Cloom and OurPCB.

I am a responsible, intelligent and experienced business professional with an extensive background in the electronics industry.

Reach me at [email protected] to get a quote for your projects.


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