I have this spoke tool. The number I use on this tool is 14. I use it on a hybrid mountain bike.
I want to get one which is easier to use but I do not know which size.
Here are the available sizes.
For 3.20mm/80 ga./0.127" nipples, black vinyl coated.
For 3.45mm/80 ga./0.136" nipples, red vinyl coated.
For 3.30mm/80 ga./0.130” nipples, green vinyl coating
My guess is the red one in the middle. Hoping for someone to confirm my guess.
Edit by Moz: Bounty offered for a conversion chart or link to one. Those numbers seem more or less consistent on the three of those tools I found, so somewhere there has to be a reference to the expected sizes (unfortunately theres +/- .1mm wear on the ones I have as they're old and cheap). The suppliers I've found all just say "fits all sizes" and don't list what the sizes actually are.