Wire Gauges explained
All wire fencing is sold in weight and wire thickness, the general rule of thumb the lower the gauge the thicker the wire, general uses for wire of 19g or higher is for keeping in chickens and aviary, fruit cages, 16g is the entry level for dog mesh, and 12g and used for security fencing or large dogs.

22G - 0.7mm thick
20G – 0.9mm thick
19G – 1mm thick
18g – 1.2mm thick
16g – 1.6mm thick
15g – 1.8mm thick
14g – 2.0mm thick
12g – 2.5mm thick
10g - 3.0mm thick
8g – 4.0mm thick