18gauge is about 1.02mm.
18 or 20 gauge
5.0 mm or 4 Guage
For a standard nostril piercing, 18 g.
If you got it gunned, its either a 20ga or 18ga. If you got it done by an actual piercer, its probably 16ga. Take the initial jewelry measure it. Look up a mm to gauge conversion chart and see what it is :)
Either 16ga or 14ga
A little over 1".
Probably 19 gauge, which is 1.067 mm
For wire gauge, 1.25 mm diameter wire is closest to 16 gauge (AWG). See related link.
12 gauge is thicker than 14 gauge.
1 mm = 4/100 inches
.953 mm (USG)