I'm sure some of you are getting tired of seeing my incessant questions about building wheels and such. So I apologize. I just don't want to order the wrong size spokes or have my wheel all jankity.

I got a rim from my LBS that I don't know the brand of. I've measured all the pertinent dimensions, but I'm confused about the rim offset.

The ERD of the rim is 615mm. The rim is 26mm wide making the half-width 13mm. The distance from the side of the rim to the nearest spoke hole is 11mm. So that would make the offset(OSB) 2mm?

When I enter ERD-615mm OSB-2mm along with the standard AW hub dimensions it gives me spoke lenghts of 292.5 for the left and 292.8 for the right. Does that sound right? Is the difference in spoke lengths only because of the rim offset? And is the reason it is such a small difference because an AW hub is not offset either?

Most importantly though, as long as my calculations are correct I don't think a .3mm difference even matters. 291mm or 292mm spokes should do the trick... I think.