Geometric Bet Sizing Calculator
One bet size, repeated every street, that gets the stack in on the last one. Enter the pot and what is behind.
Bet this share of the pot, every street
54.0%
54% of the pot on each of 3 streets gets you all-in on the last one. A standard-looking size that happens to be the exact one that lands on zero.
SPR
4
Final pot
900
Defend per street
64.9%
Left by the river
27.4%
| Street | Pot before | Bet | % of pot | Stack left |
|---|---|---|---|---|
| Flop | 100 | 54 | 54.0% | 346 |
| Turn | 208 | 112.33 | 54.0% | 233.67 |
| River | 432.66 | 233.67 | 54.0% | all-in |
What the sizes you actually use would do here
Same pot, same stack, same 3 streets.
| Size | Streets to all-in | Left behind | Verdict |
|---|---|---|---|
| Geometric (54.0%) | 3 | 0 | Lands exactly on all-in |
| One third pot | 5 | 218.53 | Leaves 54.6% of the stack behind |
| Half pot | 4 | 50 | Leaves 12.5% of the stack behind |
| Two thirds pot | 3 | 0 | All-in on street 3 — sooner than planned |
| Pot | 2 | 0 | All-in on street 2 — sooner than planned |
Guide
Geometric bet sizing, and why one size beats three
You have a hand worth stacking off with and three streets to do it in. You could bet small and then panic on the river, or bet huge and fold everything out. Geometric sizing is the third option: work out the single fraction of the pot that, bet on every street, spends the stack exactly as the river betting closes. There is only ever one such number, and it is worth knowing how to find it.
The formula
f = ( (1 + 2S)1/n − 1 ) ÷ 2
S is the stack-to-pot ratio and n is the number of bets you intend to get called. The 2 matters. A bet of f times the pot that gets called adds 2f to the pot, not f, so the pot multiplies by (1 + 2f) each street. Over n streets it multiplies by (1 + 2f)n, and the plan works when that equals 1 + 2S — your stack in, theirs matched. Solve for f and you get the line above.
The version that circulates as (1 + 2f)n = 1 + S is wrong. It solves for getting half your stack in and leaves the other half behind on the river.
Two sanity checks
With one street left, f should just be the SPR — one bet of S times the pot is the whole stack. It is: 4 at SPR 4, 13 at SPR 13. And pot-sized bets should land on the familiar numbers. They do: a pot-sized bet gets all in at SPR 1 in one street, 4 in two, 13 in three and 40 in four.
SPR 13 in three pot-sized bets is the one worth memorising, because it is the number that tells you a 100bb single-raised pot is nowhere near it. Half-pot bets over three streets need only SPR 3.5.
A worked spot
single-raised pot, 100bb: the pot is 12 and you have 94 behind, so the SPR is 7.8333. Over 3 streets the geometric size is 77.7% of the pot:
| Street | Pot | Bet | Behind |
|---|---|---|---|
| Flop | 12 | 9.33 | 84.67 |
| Turn | 30.66 | 23.83 | 60.84 |
| River | 78.32 | 60.84 | 0 |
Every bet is the same share of the pot and every bet is bigger than the last in chips, because the pot it goes into has grown. The final pot is 200.
What it does to the other player
A bet of 77.7% pot lays 56% odds on a call, so to stop you printing with any two cards they have to defend 56.3% of their range on that street. Do it three times and only 17.8% of a pure bluff-catching range is still there at showdown.
That is the actual argument for equal sizes, and it is not obvious. For a fixed number of streets and a fixed stack, betting the same fraction every street is the line that leaves the smallest share of their range alive. Any lopsided plan — small, small, huge — gets to the same all-in with more of their range intact. The MDF calculator works a single street of that in more detail.
The size for every SPR worth knowing
The geometric size for one, two and three streets, at the SPRs you actually sit down with. A size above 100% is an overbet, which no-limit allows and pot-limit does not.
| SPR | 1 street | 2 streets | 3 streets |
|---|---|---|---|
| 0.5 | 50% | 20.71% | 13% |
| 1 | 100% | 36.6% | 22.11% |
| 1.5 | 150% | 50% | 29.37% |
| 2 | 200% | 61.8% | 35.5% |
| 3 | 300% | 82.29% | 45.65% |
| 4 | 400% | 100% | 54% |
| 5 | 500% | 115.83% | 61.2% |
| 6 | 600% | 130.28% | 67.57% |
| 8 | 800% | 156.16% | 78.56% |
| 10 | 1000% | 179.13% | 87.95% |
| 13 | 1300% | 209.81% | 100% |
| 20 | 2000% | 270.16% | 122.41% |
When not to use it
Geometric sizing answers one question — how do I get all in smoothly — and it assumes you want to. That assumption does a lot of work, and it is wrong more often than the formula suggests:
- →It assumes you get called every street. Against someone folding the turn, the plan is a plan for a pot you will not reach.
- →It assumes stacking off is right. With a hand that wants three streets of thin value rather than the whole stack, the correct sizing is smaller and the correct number of streets may be two.
- →At 3-bet pot, 100bb the SPR is only 2.5, so the geometric size over 3 streets is 40.9% — small enough that the plan barely constrains you. Low SPR does the work on its own.
- →At SPR 13 it wants 100.0% of the pot three times — legal in no-limit, and illegal in pot-limit, where 3.5 is roughly the deepest a half-pot line gets in over three streets.
It is a reference line, not a rule. Knowing the size that lands exactly tells you how far any other size is from getting the money in, which is most of the value.
Related: pot odds, minimum defence frequency, and the pot-limit maximum for the games where this plan runs out of room.
Frequently asked questions
What is geometric bet sizing in poker?›
Betting the same fraction of the pot on every remaining street so that the last bet puts the stack exactly all in. Because a called bet of f times the pot grows the pot by 2f, the pot multiplies by (1 + 2f) each street, and choosing f so that it multiplies by exactly 1 + 2S over n streets is what makes the plan land on zero.
What is the geometric bet sizing formula?›
f = ((1 + 2S)^(1/n) − 1) / 2, where S is the stack-to-pot ratio and n is the number of streets you intend to bet. Check it with one street: n = 1 gives f = S, which is right, because a single bet of S times the pot is the whole stack.
Why is my geometric bet size an overbet?›
Because the stack is deep for the number of streets left. A pot-sized bet only gets all in at SPR 13 over three streets and SPR 4 over two, so anything deeper than that needs more than the pot each time. Overbets are legal in no-limit and not in pot-limit.
Why bet the same size every street instead of building up?›
Because equal fractions leave the smallest share of a bluff-catching range alive by the river. Each bet of f times the pot forces a defence of 1/(1+f), and for a fixed all-in over a fixed number of streets, the product of those survival rates is smallest when the fractions are equal. Any lopsided plan reaches the same all-in having folded out less.
Does geometric sizing work if my opponent folds?›
No, and that is its main limitation. The plan assumes every bet is called, because it is a plan for how to get a stack in, not a prediction of what will happen. Against an opponent who folds the turn, you never reach the street the arithmetic was built for.
What SPR do three pot-sized bets get all in at?›
SPR 13. The sequence is 1, 4, 13, 40 for one, two, three and four streets — each one is three times the last plus one, because a called pot-sized bet triples the pot.
Related tools
Stack-to-pot ratio and commitment threshold for post-flop play.
Minimum defense frequency and bluff break-even for any bet size.
Shove EV, the break-even fold percentage, and the equity a call needs.
Interesting spots. Solver-grade analysis.
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