In my chain maille designs, I often need loops of a specific size to match other jump rings in the pattern.
The easiest way to achieve this is by using an existing jump ring or loop that's the size you want.
Place that loop on your round nose pliers and mark the spot where it sits.
Marking the pliers with a Sharpie or other permanent marker saves time and helps keep your loops uniform.
You can mark either the metal jaws or, if your pliers have them, the nylon tips.
These marks can be removed easily with a paper towel, fine sandpaper, or rubbing alcohol.
If the loop you want to replicate is already part of a design and won't fit on your pliers, use vernier calipers to measure the inside diameter of the ring.
Then, transfer that measurement to your round nose pliers for consistent results.
Pro Tip: Using jump rings and pieces from other projects is a great way to work out the size of the loops you want to make.
Pro Tip: Sometimes the loop you want to replicate will already be attached to a piece of jewelry. Calipers or verniers can measure the inner diameter of a loop and transfer this measurement to your round nose pliers.