SPR in Poker: Stack-to-Pot Ratio Explained with Examples
Last updated: May 11, 2026
SPR (Stack-to-Pot Ratio) is a single number that tells you how committed you are to a pot and which hands are strong enough to risk your entire stack. Calculated as Effective Stack ÷ Pot size at the start of the flop, SPR organizes every post-flop decision around a simple framework: at SPR 2, top pair stacks off; at SPR 12, you need two pair or better. Coined by Ed Miller in 2006, SPR is now used by millions of players to make mathematically sound commitment decisions without complex calculations at the table.
What Is SPR and Why Does It Matter?
Stack-to-Pot Ratio (SPR) is the ratio of the effective stack to the pot size at the beginning of a post-flop street. It answers one critical question: how much money remains relative to what is already in the pot? A low SPR means the remaining stacks are small compared to the pot — there is less room to maneuver and hands commit faster. A high SPR means there is a lot of play left — stronger hands are required before risking an entire stack.
Ed Miller introduced the concept in his 2006 book Professional No-Limit Hold'em Volume 1. Before SPR, players relied on intuitive hand strength rankings. SPR gave a mathematical framework to map hand strength to stack commitment — a single number that encodes all the information needed to decide whether to stack off.
The SPR Formula
SPR = Effective Stack ÷ Pot Size
Effective Stack = the smaller of the two stacks in play
SPR matters because it determines commitment pressure. At SPR 1, if you bet the pot you are all-in — every bet is a full commitment decision. At SPR 15, you can fire 3 streets of 50% pot bets without being all-in. This landscape changes which hands are profitable stack-offs, how draws should be played, and what sizing makes sense.
SPR also provides a common language between players. When a coach says “at SPR 8, TPTK is not a stack-off,” every player can instantly visualize the situation. This precision is why SPR has become one of the 3 or 4 most important concepts in modern no-limit hold'em theory.
How to Calculate SPR: Formula and Examples
The formula is simple, but applying it correctly requires two things: always use the effective stack (not your own stack), and measure the pot before any flop action. Here are 3 worked examples across different stack depths and preflop sizings.
SPR Calculation Formula
SPR = min(stack_hero, stack_villain) ÷ pot_at_start_of_flop
Always use effective stack — the smaller of the two. Never use your raw stack.
Example 1 — Standard 100bb Cash Game
BTN opens 2.5bb, BB calls. Both start with 100bb. Pot at flop = 5.5bb (2.5 + 2.5 + 0.5bb SB dead). Effective stack = 97.5bb.
SPR = 97.5 ÷ 5.5 ≈ 17.7
Very high SPR — only premium made hands (sets+) are stack-off candidates.
Example 2 — 3-Bet Pot, 100bb Effective
UTG opens 3bb, BTN 3-bets to 9bb, UTG calls. Pot = 19.5bb. Both started with 100bb, so effective stack = 91bb.
SPR = 91 ÷ 19.5 ≈ 4.7
Medium SPR — TPTK is a reasonable stack-off; draws have reduced implied odds.
Example 3 — 4-Bet Pot, 150bb Effective
BTN opens 3bb, CO 3-bets to 10bb, BTN 4-bets to 26bb, CO calls. Pot = 53.5bb. Effective stack = 150 − 26 = 124bb.
SPR = 124 ÷ 53.5 ≈ 2.3
Low SPR — almost any top pair is a stack-off. Sets are the nuts here.
SPR Thresholds: What Hand Do You Need?
The core utility of SPR is mapping hand strength to commitment thresholds. The table below shows which hands are generally stack-off candidates at each SPR range — and which are not. These are defaults; reads and board texture can shift the thresholds by 1-2 SPR points in either direction.
A useful mental model: at SPR 3, think “this is basically an all-in call decision.” At SPR 10+, think “I need a very strong hand to put my entire stack in — top pair is just a value bet, not an all-in.” The thresholds shift on wet boards (more draws = opponents can continue wider) and dry boards (fewer draws = opponents need stronger hands to continue, which paradoxically lets you stack off with slightly weaker holdings because they represent stronger ranges).
How SPR Affects Flop Betting Strategy
SPR does not just determine stack-off thresholds — it dictates your entire approach to flop play, including sizing, whether to fast-play or slow-play, and how to structure multi-street plans. Three distinct zones of flop strategy emerge from SPR levels.
Low SPR (1–3): Bet large, commit early
At SPR 1-3, the stacks-to-pot geometry means that even a 75% pot bet on the flop puts roughly 50% of remaining stacks in. With a strong made hand, fast-play is correct almost 100% of the time — slow-playing risks losing value when scare cards arrive and giving free equity to draws. Bet 67-100% pot on the flop and be prepared to call off on the turn.
Medium SPR (4–9): Balance between fast-play and pot control
Medium SPR is the most nuanced zone. You want to build the pot with strong hands but you also have enough stack depth to exercise pot control with marginal holdings. A common approach: bet 50-67% pot on the flop with strong top pair, then decide on the turn based on the action. Three streets of 50% pot bets get stacks in cleanly by the river at SPR 8.
High SPR (10+): Slow-play, pot control, and implied odds
At SPR 10+, slow-playing strong hands (sets, two pair) is often correct because you can extract value across 3 streets and your opponents will build pots with weaker hands. Top pair wants pot control — a single bet on the flop may be enough. Draws have massive implied odds at SPR 10+ and can be played profitably even with weaker equity. A flopped flush draw at SPR 15 can call raises and re-raises profitably.
A useful sizing rule: at SPR 4, a pot-sized flop bet + pot-sized turn bet = all-in. At SPR 9, three 50% pot bets across flop, turn, and river will get stacks in by the river. Understanding this geometry lets you size each street intentionally rather than making ad hoc decisions that leave awkward stack sizes on later streets.
SPR and Drawing Hands: Implied Odds Math
SPR and implied odds are inseparable. Implied odds represent the money you expect to win from future streets after completing your draw — and the higher the SPR, the larger that future pot can be. This relationship fundamentally determines whether draws are profitable calls, profitable raises, or folds.
Set-Mining Implied Odds Rule
You hit a set ~12% of the time (1 in 8 flops)
Required: win at least 8× the call amount when you hit
→ SPR must be ≥ 10 for set-mining to be profitable in most spots
Consider a flush draw (9 outs, approximately 19% to hit on the turn). At SPR 12, the implied odds are enormous: if you hit, you can extract 10-12 big blinds on the turn and all remaining stacks on the river. The draw is a profitable call against almost any flop bet. At SPR 2, if you hit, there is virtually no money left to win — the draw becomes a borderline call at best, a fold against large bets.
Open-ended straight draws (8 outs, approximately 17% to hit) follow the same pattern. At SPR 8+, they are strong semi-bluffing candidates — you have fold equity when you bet and strong implied odds when called. At SPR 3, the draw loses its primary source of value (implied odds) and becomes a more speculative semi-bluff relying almost entirely on fold equity.
The practical rule: the deeper the effective stack relative to pot (higher SPR), the more you should pursue draws aggressively. The shallower (lower SPR), the more you need immediate equity or fold equity to justify investment in a draw.
Manipulating SPR: Preflop Sizing and Stack Management
Skilled players do not just react to SPR — they engineer it. Every preflop action you take directly determines the SPR at which post-flop play begins. Understanding this lets you set up favorable post-flop structures before a flop is ever dealt.
3-Betting to reduce SPR (favors strong made hands)
A standard 3-bet to 9-10bb preflop shrinks the flop SPR from ~17 (single-raised pot) to roughly 4-5. This is intentional when you have a hand like AA, KK, or AK — hands that play very well at low SPR because they are likely ahead and want to commit. A 3-bet effectively converts a high-SPR, implied-odds game into a low-SPR, value-driven game. Facing a 3-bet, calling with a speculative hand like 66 requires at least SPR 10 to set-mine profitably — another reason calling a 3-bet with small pairs is often incorrect.
Calling instead of 3-betting to preserve SPR (favors speculative hands)
When you have a suited connector or small pair and want high SPR, flat-calling is the correct play even when a 3-bet might be marginally profitable. Keeping SPR high (10+) maximizes implied odds for your drawing hands. This is why cold-calling 3-bets with 87s in position can be correct even at 100bb — you maintain SPR ≈ 7-8, enough to profit significantly when you flop a flush draw or two pair.
Position amplifies SPR advantages by 12-15%
Being in position at any SPR level is worth roughly 12-15% more in equity realization. At high SPR, position lets you see free or cheap turns with draws, extract value on multiple streets with made hands, and avoid tricky spots OOP. At low SPR, position lets you more accurately evaluate whether to commit — you have more information before making the final decision. Always factor in position when assessing the true value of your SPR situation.
SPR Street-by-Street: How It Changes Through the Hand
SPR is not static — it decreases with every bet and call across flop, turn, and river. A hand that starts at SPR 8 on the flop may reach SPR 1.5 by the river. This trajectory matters: you can plan multiple streets in advance by modeling how each bet reduces SPR and whether you will reach commitment threshold with your hand.
Worked Example — SPR Trajectory from Flop to River
Starting conditions: 100bb stacks, 3-bet pot, flop pot = 19.5bb, effective stack = 91bb → Flop SPR = 91 ÷ 19.5 ≈ 4.7
Flop
Hero bets 13bb (67% pot), villain calls
Turn SPR = (91 − 13) ÷ (19.5 + 26) = 78 ÷ 45.5 ≈ 1.7
SPR drops from 4.7 → 1.7 after flop bet
Turn
Hero bets 30bb (66% pot), villain calls
River SPR = (78 − 30) ÷ (45.5 + 60) = 48 ÷ 105.5 ≈ 0.46
SPR below 1 — pot-committed, all-in on river is automatic
River
Hero shoves 48bb into 105.5bb pot
SPR = 0 (all-in)
3 streets of 67% pot sizing gets stacks in at SPR 4.7
The key lesson: at flop SPR 4.7, committing 3 streets of roughly 67% pot gets all stacks in by the river. This means that on the flop, you should be thinking “I am prepared to stack off by the river if I keep betting — is my hand good enough for that?” If not, consider a smaller bet or check to control the pot and keep SPR from collapsing too quickly.
Unplanned pot commitment is one of the most common mistakes in no-limit hold'em. A player bets the flop, calls a raise on the turn, and suddenly faces an all-in on the river with a marginal hand — committed by the pot but not by their hand strength. Tracking SPR trajectory prevents this: if committing to the river is not justified by your hand, size down or check earlier in the hand.
Definitions
Frequently Asked Questions
What is SPR in poker?
SPR (Stack-to-Pot Ratio) measures how many times the effective stack can fill the current pot. Formula: SPR = Effective Stack ÷ Pot. Example: $200 pot after preflop betting, effective stack is $800 → SPR = 800/200 = 4. SPR is calculated at the start of the flop (or turn if first calculated there). It tells you how committed you are to the pot and how strong a hand you need to risk your entire stack. Low SPR means it is easier to stack off; high SPR means you need a premium hand to go all-in. The concept was popularized by Ed Miller in Professional No-Limit Hold'em Volume 1 (2006) and has become a cornerstone of modern cash game theory.
How do you calculate SPR?
SPR = Effective Stack (the smaller of the two relevant stacks) ÷ Pot size at the start of the relevant street. Always use the effective stack, not your full stack. Example 1: You have $500 behind, opponent has $300, pot is $100 → SPR = 300/100 = 3. Example 2: 100bb stacks, preflop pot is 6.5bb after a 2.5bb open and call → SPR at flop = 96.75bb ÷ 6.5bb ≈ 14.9. Higher SPR means deeper effective stacks relative to pot. The calculation is done at the beginning of each street, so SPR naturally decreases as bets go in on successive streets.
What SPR should I stack off with top pair?
It depends on the SPR level. Low SPR (1-3): Stack off with top pair/any kicker — pot commitment threshold is reached. Medium SPR (4-6): Stack off with top pair/top kicker only if opponent is an aggressor or there is significant draw equity in the pot. SPR 7-10: Top pair/top kicker is borderline; you need specific reads or villain tendencies to commit. High SPR (10+): Top pair is not a stack-off hand in most scenarios — two pair or better required. The threshold concept is this: if committing your remaining stack would make calling worse than folding based on equity, do not commit. A good default is to only stack top pair when SPR is 4 or below.
How does SPR affect flop strategy?
SPR fundamentally changes what hand strength is required for commitment. At SPR 2, any top pair/decent kicker can profitably stack off because implied odds and fold equity combine to make it EV+. At SPR 12, even TPTK may only be profitable as a value bet (not all-in), because the risk:reward ratio shifts dramatically. SPR also affects drawing hands: at high SPR (10+), draws have better implied odds — more money to win after completing; at low SPR (1-3), draws lose value because there is far less money behind to extract. A 9-out straight draw that is hugely profitable at SPR 10 may not justify a raise at SPR 2 because the implied odds simply are not there.
What SPR favors sets?
Sets (three of a kind flopped with a pocket pair) profit most at medium-to-high SPR (6-15). At SPR 8+, sets earn enormous implied odds — opponents will stack off with top pair, two pair, and even lower sets. At very low SPR (1-2), sets are still profitable but the upside is capped because there is not much money left to win. Set-mining (calling preflop with small pairs to flop a set) requires implied odds of roughly 10:1 or greater, which means SPR should be at least 10 for the call to be mathematically sound. Hitting a set roughly 12% of the time (about 1 in 8), you need to win at least 8 times the call amount when you do hit to break even.
How does SPR change from street to street?
SPR decreases as each street is bet. Starting flop SPR of 8 → if you bet 67% pot and opponent calls, the turn SPR drops to roughly 4. Continue to the river with another 67% bet and SPR approaches 1.5. This dynamic matters: a hand that is not a stack-off at SPR 8 on the flop might reach the commitment threshold by the turn at SPR 3-4. Planning your hand through SPR projections helps you avoid accidental pot-commitment — the situation where you have bet enough that calling off the rest is mathematically forced even though you do not want to. Always think one street ahead when considering your SPR trajectory.
How do I manipulate SPR to my advantage?
You can control SPR through preflop sizing and action. Raise larger preflop (3bb vs 2bb) to shrink SPR — useful when you have premium hands that play well at low SPR (sets, overpairs, strong top pair hands) or when you want to reduce your opponent's drawing odds. Call preflop instead of 3-betting to keep SPR high — useful with speculative hands (small pairs, suited connectors) that profit from high SPR implied odds. Position also matters: being in position at any SPR level is worth roughly 12-15% more in equity realization, which amplifies every SPR advantage you hold over the hand.
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