How to Determine Wire Sizes for Stranded Copper Wire

Wire gauge size is measured and described in two different ways: American Wire Gauge and Metric Wire Gauge.

Stranded copper wire can be measured to determine its size.Stranded copper wire can be measured to determine its size.
American Wire Gauge is measured in inches per diameter of the wire; Metric Wire Gauge is measured in millimeters per diameter. The American formula below can easily be converted to metric gauge.

Strip 1/2 inch off the end of a copper strand wire. Twist the wire together in your fingers so that all of the strands become braided together.

Measure the end diameter of the twisted copper wire strands with a regular ruler. Better yet, use a wire gauge ruler to measure the diameter of the twisted strands. Twisted copper strands can literally be inserted into the holes of a wire gauge ruler. The precise size can be determined depending on what size hole the wire fits into.

Compare the size of the wire diameter to a wire gauge sizing chart. For example, a wire diameter of 1/4 inch will be a #2 gauge wire. A wire that measures 1/10 of an inch will be a #10 gauge wire.

Things You Will Need

  • Wire stripper
  • Ruler or wire gauge ruler
  • Wire gauge sizing chart


  • A fast and easy-to-use wire gauge chart can be found on the Internet by punching in "wire gauge table" into any search engine.

About the Author

Dale Yalanovsky has been writing professionally since 1978. He has been published in "Woman's Day," "New Home Journal" and on many do-it-yourself websites. He specializes in do-it-yourself projects, household and auto maintenance and property management. Yalanovsky also writes a bimonthly column that provides home improvement advice.