In respect to this, how do I know what size my piercing is?
The measurement that you need is the distance from the piercing hole to the edge of your ear. Take this measurement in a straight line, because if you measure at a diagonal angle you will end up with a hoop that fits larger than you anticipated.
Keeping this in consideration, will a 16 gauge fit in normal piercing?
Yes you can, in fact that’s typically what a piercer will do, especially with cartilage piercings. They pierce with a gauge size bigger than the actual jewelry. It allows room for swelling and placing the jewelry.
How many mm is a standard earring?
An 18 gauge, one of the smallest gauges, is actually smaller than a 16 gauge earring, with the largest gauges being 0, 00, and 000 gauge jewelry.