Poker M-Ratio Calculator
How many rounds can your stack last? M is how many orbits of blinds and antes your stack can pay for: the number that says whether you still have room to play poker or have to start moving chips. Enter the structure for your M, your effective M at a short table, and what the same stack is in big blinds.
Example filled in: a middle level with a big blind ante, nine players. Change anything.
Step 1: How many chips do you have?
Step 2: What are the blinds and the ante?
One ante a hand, posted by the big blind. The same for a full table or a short one.
Step 3: How many players are at the table?
From 2 to 10 players. Fewer players means the blinds come round faster.
Folding every hand, your 12,000 chips pay the blinds and antes for 12 full rounds of the table, 108 hands. That is an M of 12: the yellow zone.
Your 12,000 chips pay for 12 full rounds (an is one round):
You can fold 12 complete orbits before the blinds take the stack. Speculative hands stop paying. You can no longer call a raise and fold the flop often enough to make small suited hands work, so value shifts towards hands that can stand a reraise and towards taking the initiative yourself.
Exact · M = stack ÷ (small blind + big blind + all antes for one hand); effective M = M × players ÷ 10
Why
What one hand puts in the middle, the ante included:
One hand puts 1,000 in the middle before anyone acts: the 200 small blind, the 400 big blind and the 400 big blind ante. Over one round you post each blind once and the ante once, when you are the big blind, so a round costs you 1,000 too. Your 12,000 covers 12 rounds: that is M. In big blinds the same stack is 30: each round costs 2.5 big blinds once the ante is in.
Where the numbers come from
One hand's forced money is 1,000, and folding a full orbit costs you the same 1,000, which is why M counts orbits. Each unit of M is 2.5 big blinds at this structure.
Harrington's zones, one by one
Green, M 20 and above. Nothing is forced. You can pay to see a flop and fold it, because twenty orbits of blinds are still behind your stack, so implied-odds hands are worth their price and you can lose a pot without losing the tournament.
Yellow, M 10 up to just under 20 (you are here). Speculative hands stop paying. You can no longer call a raise and fold the flop often enough to make small suited hands work, so value shifts towards hands that can stand a reraise and towards taking the initiative yourself.
Orange, M 6 up to just under 10. Your opening raise is most of a commitment: raise, get reraised, and you are calling off or folding a third of your stack. This is where stealing the blinds stops being a bonus and becomes the plan, and where first-in raises start being shoves.
Red, M 1 up to just under 6. All-in or fold, before the flop, and mostly from late position. There is no postflop game left to play with this stack, so the only decisions left are which hands and from which seat.
Dead, M below 1. You cannot fold your way through one more orbit, so the blinds will take the stack whatever you do. The hand you commit with is the best one you are dealt before the money runs out, not the best one you can imagine.
The names come from Dan Harrington's Harrington on Hold'em: one author's framework rather than a theorem. The scale shades them by how much room they leave, not by colour name.
What to do about it
M tells you how much time you have, not which hand to play. For the shoving decisions a low M forces, a short stack uses the push/fold chart. For what a pot is worth when the money is close, the ICM calculator and the bubble factor calculator price the risk. If you are building the structure rather than playing it, the blind structure calculator shows what your levels do to everyone's M.
What M means, and why big blinds alone mislead you
M is your stack divided by what one hand costs in blinds and antes. Because you pay a small blind once, a big blind once and the antes once each per orbit, that same number is how many complete orbits you could fold through before the blinds took everything. It is the honest measure of how much time you have left.
The formula
M = stack ÷ (small blind + big blind + all antes for one hand)
At 200/400 with a 400 big blind ante, one hand puts 1,000 in the middle before anyone acts. A stack of 16,000 (forty big blinds) is therefore an M of 16, which is the yellow zone.
The same forty big blinds at level one, 100/200 with no ante, is an M of 26.67, the green zone. Identical big-blind count, and 10.67 orbits of difference in what it can survive. That gap is what antes do, and it is why a player counting only big blinds misjudges the late levels.
The same stack in big blinds and in M
| Stack | M at 100/200, no ante | M at 200/400 + 400 BB ante |
|---|---|---|
| 100 big blinds | 66.67 (Green) | 40 (Green) |
| 50 big blinds | 33.33 (Green) | 20 (Green) |
| 30 big blinds | 20 (Green) | 12 (Yellow) |
| 20 big blinds | 13.33 (Yellow) | 8 (Orange) |
| 10 big blinds | 6.67 (Orange) | 4 (Red) |
Read the bottom row: ten big blinds is a desperate stack at any level, but with antes in it is worth 4 orbits rather than 6.67, which is the difference between having one more look and having none.
Harrington's zones, and what they are
The zone names come from Dan Harrington's Harrington on Hold'em. They are one author's framework rather than a theorem, and they are useful because they name the point at which your options actually close off, not because the boundaries are exact.
| Zone | Range | What it constrains |
|---|---|---|
| Green | M 20 and above | Nothing is forced. You can pay to see a flop and fold it, because twenty orbits of blinds are still behind your stack, so implied-odds hands are worth their price and you can lose a pot without losing the tournament. |
| Yellow | M 10 up to just under 20 | Speculative hands stop paying. You can no longer call a raise and fold the flop often enough to make small suited hands work, so value shifts towards hands that can stand a reraise and towards taking the initiative yourself. |
| Orange | M 6 up to just under 10 | Your opening raise is most of a commitment: raise, get reraised, and you are calling off or folding a third of your stack. This is where stealing the blinds stops being a bonus and becomes the plan, and where first-in raises start being shoves. |
| Red | M 1 up to just under 6 | All-in or fold, before the flop, and mostly from late position. There is no postflop game left to play with this stack, so the only decisions left are which hands and from which seat. |
| Dead | M below 1 | You cannot fold your way through one more orbit, so the blinds will take the stack whatever you do. The hand you commit with is the best one you are dealt before the money runs out, not the best one you can imagine. |
The calculator classifies on the exact M rather than the rounded figure, which matters only at an edge: a stack that displays as M 1.00 but cannot quite pay for one orbit is dead, not red, and saying otherwise would flatter it.
What each M is worth in chips
| M | Chips at 100/200 | Chips at 200/400 + ante |
|---|---|---|
| M 40 | 12,000 (60 bb) | 40,000 (100 bb) |
| M 20 | 6,000 (30 bb) | 20,000 (50 bb) |
| M 10 | 3,000 (15 bb) | 10,000 (25 bb) |
| M 6 | 1,800 (9 bb) | 6,000 (15 bb) |
| M 3 | 900 (4.5 bb) | 3,000 (7.5 bb) |
Effective M: a short table eats you faster
At a full table the blinds reach you once every nine or ten hands. Five-handed they reach you twice as often, so the same stack has half the time. The usual adjustment is to multiply M by players ÷ 10, and it is a convention rather than a derivation, but the direction is unarguable, and it is the reason a stack that felt comfortable becomes a shoving stack the moment the table breaks.
| Players | M | Effective M | Zone |
|---|---|---|---|
| 9-handed | 12 | 10.8 | Yellow |
| 6-handed | 12 | 7.2 | Orange (down one) |
| 5-handed | 12 | 6 | Orange (down one) |
| 3-handed | 12 | 3.6 | Red (down one) |
| 2-handed | 12 | 2.4 | Red (down one) |
Same 12,000 chips at 200/400 with a 400 ante throughout. Only the seat count changes.
Common structures, at forty big blinds
| Structure | One hand costs | M |
|---|---|---|
| Level 1: 100/200, no ante | 300 | 26.67 (Green) |
| Level 8: 500/1,000, 100 ante from everyone | 2,400 | 16.67 (Yellow) |
| Level 8: 500/1,000, 1,000 big blind ante | 2,500 | 16 (Yellow) |
| Final table: 3,000/6,000, 6,000 big blind ante, 6-handed | 15,000 | 16 (Yellow) |
The cash-game question: "What is 100bb?"
A big blind is one unit of the stake, so a hundred big blinds is a hundred times the big blind in money. That is the standard buy-in for a cash game, and it is why stacks are quoted in blinds rather than currency: the strategy is identical whatever the stake.
| Stake | 100 big blinds | 40 big blinds |
|---|---|---|
| $0.05/$0.10 | $NaN | $NaN |
| $0.25/$0.50 | $NaN | $NaN |
| $1/$2 | $NaN | $NaN |
| $2/$5 | $NaN | $NaN |
| $5/$10 | $NaN | $NaN |
M is a tournament idea and does not really apply to a cash game: there are no rising blinds to outrun and you can reload, so a cash stack is measured in big blinds and in stack-to-pot ratio instead.
Using it
M answers how much time you have. What to do with the time is a different question: the push/fold chart covers the shoving ranges a low M forces, the bubble factor calculator prices the risk when the money is close, and the ICM calculator values the stack in actual money. Hosting rather than playing? The blind structure calculator shows what your level lengths do to everyone's M, and what is ICM in poker explains why chips stop being money.
Frequently asked questions
What is M in poker?›
M is your stack divided by the cost of one hand in blinds and antes: the small blind plus the big blind plus every ante posted that hand. Because you pay each of those once per orbit, M is also the number of complete orbits you could fold through before the blinds took your stack. At 200/400 with a 400 big blind ante, one hand costs 1,000, so a 16,000 stack has an M of 16.
What is a good M ratio?›
Above 20 nothing is forced: you can pay to see a flop and fold it. Between 10 and 20 speculative hands stop paying for themselves. Between 6 and 10 you are looking for a spot to commit, and below 6 you are choosing which hand to go with rather than how to play a pot. Those bands are Harrington's zones: one author's framework, not a theorem, and useful because they name where your options close rather than because the edges are exact.
How is M different from counting big blinds?›
Big blinds ignore the antes, and the antes are most of the cost late in a tournament. Forty big blinds at 100/200 with no ante is an M of 26.67; the same forty big blinds at 200/400 with a 400 ante is an M of 16. Same stack in blinds, 10.67 fewer orbits of survival.
What is effective M?›
M adjusted for a short table: multiply by the number of players divided by ten. Five-handed the blinds reach you twice as often as they do ten-handed, so the same stack has half the time. It is a convention rather than a derivation, but the direction is not in doubt, and it is why a comfortable stack becomes a shoving stack as soon as the table breaks.
What is 100bb in poker?›
A hundred big blinds: a hundred times the big blind of whatever game you are in. It is the standard cash-game buy-in, which is why stacks are quoted in blinds rather than money: 100bb plays the same whether the big blind is ten cents or ten dollars.
Does M matter in a cash game?›
Not really. M measures how long you can outrun rising blinds, and a cash game has none, plus you can reload at any time. In a cash game the useful measures are the stack in big blinds and the stack-to-pot ratio once a hand is under way.
How does a big blind ante change M?›
It adds one ante to every hand rather than one from each player, so it costs a full table much less than an equivalent per-player ante. Reading a big blind ante as if every player posted it would make a nine-handed M look several times smaller than it is, which is the mistake this calculator exists to stop. Pick the right ante type and the figure moves accordingly.
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