Geometric Bet Sizing

Overview

Geometric bet sizing (G-Bet) is a concept in no-limit hold'em that refers to betting a consistent percentage of the pot on each street (flop, turn, river) so that the final pot size on the river is a predetermined multiple of the initial pot. The term “geometric” comes from the mathematical progression of pot growth: if you bet a fraction b of the pot each street, after n streets the total pot is multiplied by (1 + b)^n. This approach is often used when you want to get all-in by the river with a balanced range, as it forces opponents to make tough decisions at each step.

Why Use Geometric Bet Sizing?

In modern poker theory, particularly in Game Theory Optimal (GTO) strategies, bet sizing is chosen to make opponents indifferent to calling or folding with their marginal hands. A common reason to use geometric sizing is to commit a specific amount of chips by the river — often the effective stack. For example, if the pot on the flop is 10 big blinds (BB) and the effective stack is 80 BB, a geometric bet size of about 67% pot on each street (flop, turn, river) will result in a pot of 80 BB by the river, allowing a shove on the river. This ensures that the entire stack can be bet in a way that is proportional to the pot.

How It Works

Suppose the pot on the flop is P and you want to bet a fraction f on the flop, turn, and river such that after three bets the final pot equals the effective stack size S (plus the original pot). The formula for geometric sizing is: if you bet f of the pot each street, after the flop bet the pot becomes (1+f)P, after turn it becomes (1+f)^2 P, and after river it becomes (1+f)^3 P. Setting this equal to the final pot (which includes all bets) can be solved for f. In practice, players often use approximations or common sizes like 2/3 pot, 3/4 pot, or pot-sized bets.

Example

Scenario: You have a strong hand and want to get all-in by the river. The pot on the flop is 20 BB, and effective stacks are 100 BB.

Using geometric sizing:

• Bet 75% pot on flop: pot becomes 20 + 15 (bet) + 15 (call) = 50 BB.
• Bet 75% on turn: pot becomes 50 + 37.5 + 37.5 = 125 BB.
• On river, you can bet the remaining 47.5 BB (since you started with 100 BB, you've bet 15 + 37.5 = 52.5, leaving 47.5) into a pot of 125 BB, which is about 38% pot. Alternatively, adjust sizing to end exactly all-in. The key is that the geometric fraction ensures the stack is committed evenly across streets.

When to Use Geometric Bet Sizing

• Value betting: When you have a strong hand and want to maximize value against opponents who may call down with weaker hands.
• Bluffing: When you want to apply maximum pressure with a balanced range, so your bluffs have the same sizing as your value bets.
• All-in scenarios: When effective stacks are deep and you plan to bet three streets, geometric sizing simplifies the decision tree.
• Multi-street aggression: In situations where you want to deny implied odds to draws, geometric bets make it unprofitable for opponents to chase.

Limitations

Geometric bet sizing is a theoretical concept; in practice, players adjust based on board texture, opponent tendencies, and stack sizes. It assumes the opponent will call all bets and that the hand plays out to the river, which is not always the case. Also, it is most useful when you have a polarized range (strong hands and bluffs) rather than merged ranges. Many players use a mix of sizings to avoid being predictable.

Conclusion

Geometric bet sizing is a powerful tool for planning multi-street bets in no-limit hold'em. It helps players structure their bets to maximize pressure or value while maintaining balanced ranges. Understanding the math behind it can improve your ability to commit stacks efficiently and exploit opponents who are unfamiliar with proper bet sizing.