$2/$4 NL Bankroll Quirements?

I apologize if this has been answered previously, and I assume that it has been, but my search didn't uncover it. What is a conservative recommendation for bankroll requirements for $2/$4 NL if you plan on 2 or 3 tabling?

I have been playing mostly tourneys since I started playing seriously, but have recently begun playing and having success at the cash games at the .50/$1 and then $1/$2 NL. I just decided to move up, but am now questioning my bankroll's sufficiency.

I'd appreciate some guidance here.

Holdemphile

Sorry, wrong forum. Will repost in NL forum.

Holdemphile