SIZING 101
Dude what is standard size and comfort fit size and my size?!? Here is a shortcut:
Standard size - what the jeweler will size you as, with a thin band. This tool will also give you that same answer. You want it to feel pretty snug, like it ain't going nowhere.
Comfort size - a domed-like shape inside the ring to help it hug your finger nicely. In short: more curves, less edges. This can fit slightly bigger in smaller widths, so you may need to size down a half size for 2mm, 4mm, or 6mm widths. See below.
HOW TO USE THE MANLY RING SIZER
Note: It's best to measure when your hands are cold, not after a Manly workout when they are likely swollen with power and ingenuity.
Unscrew the chain of small rings and find one that fits comfortably snug.
Shake your hand like you're waving goodbye to your future in-laws with glee and see if it stays in place. If so, that is your standard size! If not, keep trying.
Make sure to consider whether you want to be able to spin your ring around a lot or if you want it to go on and stay on day and night.
Let's say you're feeling good with the size 10, then:
-for a comfort fit ring in an 8mm width, choose a size 10.
-for a comfort fit ring in a 2mm, 4mm, or 6mm width, choose a size 9.5.