Chapter 1 / 6
Why you must buy in for 100bb max in micro-stakes cash game
4 min read
Buy-in is the stack you sit down with at the table. Not your bankroll, not what's left in your account. Just what you put in front of you when you click "join a table".
In micro-stakes cash game NL2 to NL100, that starting stack must be 100 big blinds. Always. It's the first setting to make before even thinking about stats or ranges. And it's surprising how many players sit down at 40bb or 60bb without asking why, or let themselves climb to 200bb without reacting.
Why 100bb exactly
All of modern cash-game poker is built for 100bb effective. The opening ranges you'll see in any course, the standard cbet sizings, the preflop equity math: everything is calibrated for that depth.
When you read a course, watch a video or use a solver, the baseline assumption is 100bb. If you play 40bb or 200bb, you're playing a different game, with different rules, without the tools for it. It's that simple: 100bb is the reference standard of modern poker.
SPR, in two lines
The SPR (Stack-to-Pot Ratio) is the ratio between what's left in your stack and the pot size on the flop. The higher it is, the more complex postflop decisions become.
At 100bb, the standard SPR of a single raised pot is around 15. That's the depth all postflop theory is written for. At 200bb, your SPR doubles, and so do your postflop decisions.
The 180-200bb cap at the table
Here's the rule nobody tells you: you buy in for 100bb. You double up, you're at 200bb. You leave the table. You switch tables and buy back in for 100bb.
It seems counterintuitive. You just won a stack, why leave? You leave because your edge in micros is on the single raised pot at SPR 10-15, not on monster pots with SPR 50. You leave because the other deep players at the table are either regs targeting you, or fish about to ship a 180bb all-in at you. Either way, the expectation is no longer yours.
What's in the full course
This page gives you the principle. The full course goes much further on this chapter:
- The detailed SPR calculation with a step-by-step worked example
- The two concrete traps of the short stack and the deep stack, shown with a mathematical example (how many bb you win or lose at 40bb vs 100bb vs 200bb on the same hand)
- The concrete action to set up on your room from your next session to automate the 100bb buy-in
- The direct link with the rest of the courses: why this rule conditions every other chapter
The full course
Online reading, for logged-in members only.
Read the full course onlineFrequently asked questions
Why not 200bb if I can afford it?
At 200bb the SPR explodes (around 30 on the flop). Your postflop decisions become huge: you might have to fold an overpair for 200bb, or pay off a 100bb value bet without the read to fold. You play doubled variance for skills you don't have yet in micros.
What if I want to play a 40bb short stack?
At 40bb you play a mechanical, almost push-or-fold game from the flop. You give up the realization equity of connectors and middle pairs, and you miss part of your winnings on big hands. Short stacking has legit uses (tournaments, specific formats) but not in micro-stakes cash game.
What do I do when my stack goes above 200bb?
You leave the table at the end of the orbit and come back to another table with a standard 100bb buy-in. Most rooms also let you set up an auto-rebuy that tops you up automatically. The details are in the full course.
Does this apply to tournaments too?
No. In tournaments the effective depth drops as the structure goes up and you often play at 20-50bb. This chapter's principles are about cash game only.