is there a general guideline for using J’sSSBO? i’m ok with the how-to (after wading through about 100 continental style videos, to find 2 english style) but none of them say if you have X stitches you should save out Y yarn or multiply your circumference by Z, etc… so anyway, a basic guesstimate for that? thanks! 
What is JSSBO?
ETA: OK, figured it out, Jeny’s Surprisingly Stretchy Bind Off. Are you trying to figure out how much yarn you’ll need for the BO? I think I’d figure about 3x what it took to knit a round.
ETA part II: Expect this BO to flare. When I used it I ended up just doing the yo before the purls or something like that and have since changed to using Russian Bind Off in pattern. There is less flare. You may like SSBO just fine but I gave you the link just in case you want to try another.
Search for Russian bind off English style on youtube.
that’s the one - sorry, i figured the acronym was famous enough for this forum, but then again, i know i look up a ton of knitting shorthand constantly… 
jeny’s got rave reviews all over the place, but from the visuals, i was thinking it flared a lot too and that wouldn’t be my preferred finished look.
thanks for the russian option will take a look at that, and go over some of my books again too, and see what ends up as the more workable option for me.
In case you’re interested, here’s the link to my JSSBO adventure.
http://www.knittinghelp.com/forum/showthread.php?t=109175&highlight=stretchy
i was just about to ask a question about Jeny’s bind off. a different question. and then i found this thread that i started. apparently great minds have trouble thinking, again.
i’ve been told the flare that happens with J’sSSBO is mitigated by working it very tightly. i’m wondering if i went down a size or two in needles instead, and worked it regularly… would that have the same effect? or is that a bad idea, since it could be worked way too tightly unintentionally, and lose its stretch?
I have abondoned JSSBO because I find I prefer others. However I did play around with it. http://www.knittinghelp.com/forum/showthread.php?t=109175 I don’t remember doing an afterthought thumb and I have no clue for whom were the mittens I said that I made. Anyhow, that’s all the help I can offer.
“nancy drew and the case of the mysterious mittens”?
thanks for the thread and video link. the most recent one i’ve seen was elizabeth green musselman at dark matter knits. she had it as a technique at the end of one of her podcasts, and that’s where i heard that it needs to be done tightly to reduce/prevent flare. i think i’ll go down just one size and work it with my regular tension. we’ll call it a learning experience. 