Guide for understanding wire gauge and resistance


The AWG is a logarithmic scale, so given an know resistance or diameter for a certain gauge, you can quickly figure out the resistance and diameter of another gauge number, by addition and subtraction.

Resistance:

  1. AWG 15 is 10 mohm/m.
  2. Adding 3 doubles the resistance, and subtracting 3 halves it.
  3. Adding 10 multiplies the resistance by 10, and subtracting 10 it divides by 10.

Diameter:

  1. AWG 18 has a solid diameter of about 1mm
  2. Adding 6 halves the diameter, Subtracting 6 doubles the diameter
  3. Adding 20 divides the diameter by 10, and subtracting 20 multiplies the diameter by 10.

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ptss
Ptss, I understand you posted this in the context of the speaker cable resistance.  Please take into consideration that most of the speaker impedance is resistive.  8 ohm speaker  will have, most likely, resistance of 6 ohm.  Your 10 mohms, in comparison, means nothing. 
"8 ohm speaker will have, most likely, resistance of 6 ohm."

TOTAL NONESENSE!

The typical 8 ohm speaker has a "roller coaster", of varying, impedance (resistance, capacitance, inductance), across the audible audio frequency spectrum.



 
Read carefully again - RESISTANCE.  As for impedance - it usually doesn't drop below couple of ohms making 10 miliohms irrelevant.
Thanks PTSS, being a European AWG makes little sense to me. Now I can easily convert to units that I understand.
People usually think of speaker gauge when they calculate Damping Factor forgetting that speaker/driver resistance is in series with back EMF making best effective DF around 1.25
ptss, please explain to me how AWG is a logarithmic scale???
Just another take on the rule of thumb that wire diameter doubles for each 3 AWG unit decrease (i.e., #3 is twice the diameter of #6).

Adding three doubles the resistance since the area is halved and resistance is proportional to the inverse of the cross-sectional area per unit length.


Just another take on the rule of thumb that wire diameter doubles for each 3 AWG unit decrease (i.e., #3 is twice the diameter of #6).
#3 diameter is 0.2294" while #6 is 0.1620"
Wire diameter doubles for each 6 AWG decrease.