How to Find the Diameter of a Copper Wire


Copper wires are categorized by their American Wire Gauge, or AWG, size. A wire's AWG size enjoys an inverse relationship with its diameter; the lower the AWG, the thicker the wire and the heavier the current load it is able to carry. Conversely, a higher AWG indicates a thin, low-capacity copper wire. AWG tables provide a handy reference that tell you the diameter of any copper wire, given its AWG category. If you don't have a table on hand, you can still find the diameter of a copper wire with a few calculations.

Things You'll Need

  • AWG Table
  • Realize that 1 AWG = 289.3 thousandths of an inch, 5 AWG = 181.9 thousandths of an inch and 10 AWG = 101.9 thousandths of an inch. When reading an AWG table, notice that diameter is given in terms of "mils," which stands for thousandths of an inch.

  • Remember that copper wire diameters increase and decrease by a factor of two every six gauges, three every 10 gauges, 10 every 20 gauges and 100 for every 40 gauges.

  • Use 50 AWG = 1 mil as a base point. Using the general formula from Step 2, you can easily determine that 30 AWG has a diameter of 10 mil (50 - 30 = 20 and 10 mil every 20 gauges yields 30 AWG = 10 mil diameter).


  • Photo Credit spindle of copper wire on white background image by phizics from
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