hmm, I've been getting that question a lot lately. I think it needs a Kandi FAQ entry

Anyway... it would be hard for me to give you an accurate estimate of the length of string, because it depends on how often you tie off (e.g. after every row or after every ten rows). And possibly even how tight you pull/what type of string. What I personally do is just use as much as I'm comfortable working with and then tie more on if I need it.

I've never attempted to connect the number of columns/beads to a length of string because there are too many factors involved.