Measuring Wire and Metal

Updated: 1/28/17


How do you determine what size metal or wire you have

The B&S Gauge (American) is based on dividing an inch into 1000 units. Since we all love shortcuts, these one thousands of an inch are called mil. It is now known as AWG (American Wire Gauge). The measurements are the same. The British use the British Standard Wire Gauge, which is also known as, Imperial Wire Gauge or British Standard Gauge.Currently, the standard for measurement is BS (British Standard) 6722 which was instituted in 1986 and is a metric system.

Understanding a B &S or AWG wire gauge.  

The lower the number on the gauge, the bigger the wire.  So, 30 gauge wire will be very thin and 0 gauge,  very thick.

Don’t put the metal into the center hole – it fits into the outer cut.  Push the metal into the slot that fits the snuggest.

You don’t want the metal to slide in, just to barely fit.  Usually,  I will check the gauge, twice, by sliding the metal into the slots above and below, the best fitting slot, to double check. The number above the slot is the size.

There are two sets of numbers on the gauge.  One side is the AWG number.   On the back side, you will see numbers like: .257, .064, etc.  These numbers represent the size in one thousandth of an inch or mils. Ergo, .032 would be read 32 mils.


Another way to measure wire and metal is to use Calipers.

 Digital Calipers

There are digital and manual calipers available.  You can get digital calipers very cheaply but, try to get the best that you can afford as the cheapies don’t last long. They can cost anywhere between 10.00 and hundreds of dollars US.

Manual CalipersThe front end of the Calipers is used to measure external size and the end is used to measure internal spaces like, the inside of tubing or a setting.

To Use

Before use, fully close the Calipers.  If they are digital, turn them on and zero out the readout.  Check to ensure that they are set to either millimeters or inches. Using the knurled knob, on the bottom side and near the jaws, open them up.  Insert the object to be measured and close the jaws.  Check the readout for size.  The internal jaws work the same way except, the jaws fit inside an object and then they open instead of close.

Once you’ve got your measurements, you need to mark and square your metal.  To do this, please see the following pages:

Related Webpages

Related Videos