I'm confused as to why anyone would ever actually need this measurement. If you're concerned with your chainline being a few mm off from what the internet deems "perfect" (the ever-elusive 42mm), stop losing sleep over it. Considering all brands of cogs don't have the exact same tooth to shoulder dimensions, you're never going to get it 100% right.

At any rate, my digital caliper gives me close to 36mm.