Buy-In

Also known as: buyin, bi, buy in

The amount it costs to enter a game; also the unit bankrolls are measured in (bi).

"Buy-in" carries two related meanings:

1. The cost of entry. In a tournament it's the prize-pool portion plus the fee (a $109 = $100 + $9 juice). In cash it's the amount you sit down with — capped between a table minimum and maximum, usually 40–100 big blinds for NLHE (100bb is the standard "full" buy-in).
2. The bankroll unit (bi). Rolls are counted in buy-ins, not dollars, because the buy-in count is what sets your risk of ruin and variance exposure. "30 buy-ins" means the same risk profile whether you play 50NL or 500NL.

A few practical points:

• Sit with a full 100bb stack in cash unless you're deliberately short-stacking — buying in short caps your implied odds and your ability to win big pots against deep recreational players.
• Re-buy to the cap after winning a stack; playing 250bb deep against a weaker, shorter player is a real edge you forfeit by not topping up.
• In tournaments, late registration and re-entry change the effective cost of "a buy-in" — multiple bullets in one event multiply your invested buy-ins for ROI purposes.