I've recently been looking at my old collection of 15mm figures as part of my Five Year rule.
A long time ago I played Warhammer Fantasy Battles in 15mm and built up quite a collection of several different armies. I also collected some historical armies for Warhammer Ancient Battles. Eventually I moved back to 28mm and gradually sold off the armies, keeping a few of the bits I was most pleased with (including my Empire army) and the usual gamer's box of lead.
When Mantic released their Uncharted Empires book I saw the opportunity to re use my Empire as League of Rhodia, if only I could work out what base size to use.
I wanted something that was easy to calculate, didn't need much in the way of new measuring, and gave bases large enough to fit the recommended number of minis on. The small scale Kings of War Facebook group has recommended sizes (half the 28mm dimensions), but these seem to be mostly used for 10mm or 6mm (with lots of extra minis). The few 15mm I have seen at their size look cramped, and/or short of minis. So i would have to come up with my own. As long as my friends had the same size, it should be fine.
Much experimentation later and a size of 3/5ths the 28mm dimensions seems to look good. It's easy to calculate and looks good with full figure count units. It does mean making measuring sticks, but you can't have everything.
So, here's a photo showing some of my rebased troops. I've still to texture the bases, but it shows how they look.
Since these were already painted, I can't really put them in my monthly totals. I hope I can get my Vanguard goblins ready soon though.