Standard chain pitches in the smaller sizes are.
3/8"
3/8" Low Profile
.325" pitch (I've not got any idea where they came up with this size
but it is standard).
1/4" pitch.

Isn't there also a pitch that alternates drive links of one length
(I think .375) with sideplates of another (either .325 or .25),
that's also used on smaller saws?

--Glenn Lyford