Your psychological bankroll in essence is the amount of money you need to feel comfortable about riding out swings within the game of poker. I use it in terms of % of monetary bankroll and in terms of Big Bets in limit and max buy ins in No Limit Hold 'em. Some players have a higher stress tolerance for losses and some have very little. The higher your stress tolerance is the fewer buy ins or Big Bets you need for a particular game.
An example of this would be a person who doesn't use their bankroll for living expenses and wouldn't have a problem losing a large chunk of bankroll in one session would be adequate with 10 buy ins for No limit Hold 'em or 300 Big Bets for limit. On a bad day they may lose around a third of their entire bankroll.
The other extreme is the quintessential poker pro who makes his living playing the game. The psychological bankroll required for this particular player may very well be 25 buy ins for no limit or 1000 Big Bets and higher in limit if they need to withdrawal their monthly "nut" for their living expenses. They need to have some cushion built into their bankroll to ride out some swings and not affect their play. Some pro's risk tolerance is for even higher amounts of Big bet ratios to virtually eliminate their risk of ruin. That way on a very bad day they may lose 10% of their bankroll or less.
