📐 What Is SPR?
The Stack-to-Pot Ratio (SPR) measures how deep the effective stacks are relative to the pot size at the start of a street — typically calculated on the flop. It is one of the most powerful planning tools in poker because it immediately tells you how much leverage remains in the hand.
$$\text{SPR} = \frac{\text{Effective Stack}}{\text{Pot}}$$The effective stack is the smaller of the two players' remaining stacks — you can only win what your opponent has (and vice versa).
Interpreting SPR Categories
- SPR < 1: Very shallow. Pot-committed. Any reasonable hand should go all-in.
- SPR 1–4: Low. Top pair is typically committed. Most drawing hands need strong equity or fold.
- SPR 4–13: Medium. The standard 100BB deep game often produces SPR 6–10 on flop. Requires stronger hands to stack off — sets, two pair, strong top pair with nut kicker.
- SPR 13+: Deep. Only premium hands (sets, straights, flushes, nut hands) should happily put in the whole stack. High implied odds for speculative hands.
🎯 SPR and Commitment
A player is committed when folding would be a mistake regardless of what hand the opponent holds — because you have already invested so much relative to the remaining stack that the pot odds on any call are too good to fold.
The commitment threshold is approximately:
$$\text{Committed when SPR} \leq \frac{1}{\text{Required Equity} \times 2 - 1}$$For a hand like top pair (roughly 70% equity at showdown against a reasonable range), commitment occurs around SPR 1–2. For a mediocre hand like second pair (45% equity), commitment never really occurs at normal SPRs.
The Pot-Committed Calculation
You are pot-committed when calling off the remaining stack is +EV regardless of opponent's holding. With a pot of $P$ and remaining stack of $S$:
$$\text{Pot-committed when: } \frac{S}{P + S} < \text{Equity}$$Example: Pot = $200, remaining stack = $50 (SPR = 0.25). You need only \(\frac{50}{250} = 20\%\) equity to call. Almost any hand with two live cards has 20% equity, so you are pot-committed.
🃏 SPR Categories and Hand Selection
Different hand types perform very differently at various SPRs. This table summarizes which hands benefit from which stack depths:
| SPR Range | Good Hands to Stack Off | Risky Hands | Notes |
|---|---|---|---|
| 0–1 | Any pair, any draw, overcards | Nothing (always call) | Already committed; fold equity near zero |
| 1–4 | Top pair, overpair, strong draws | Weak draws (gutshot) | Top pair is a stack-off hand |
| 4–13 | Sets, two pair, strong TPTK | Top pair weak kicker, draws | Standard 100BB depth; sets preferred |
| 13+ | Sets, straights, flushes, nut hands | TPTK, overpairs | Deep stacks; implied odds king |
This is why small pocket pairs (22–66) become more valuable in deep-stack games — they rarely win a big pot with just the pair, but when they flop a set at a high SPR, the implied odds are enormous.
🔢 Three Worked Examples
Example A: SPR 2 with Top Pair TPTK
Pre-flop: You raise to 3BB, BB calls. Pot = 6.5BB. Effective stacks = 97BB remaining. Flop: \(\text{K}♠\text{7}♦\text{2}♣\). You hold \(\text{A}♠\text{K}♥\).
$$\text{SPR} = \frac{97}{6.5} \approx 14.9$$Wait — this is actually a high SPR scenario. Let's adjust: imagine this is a 3-bet pot. You 3-bet to 10BB, villain calls. Pot = 21.5BB. Effective stacks = 90BB.
$$\text{SPR} = \frac{90}{21.5} \approx 4.2$$SPR 4.2 with TPTK on a dry board. You are happy to bet and call off. The pot needs only 2–3 more streets of betting to get stacks in. With AK on K72, commit freely.
Example B: SPR 6 with a Set
In a single-raised pot, pot = 13BB, effective stacks = 80BB.
$$\text{SPR} = \frac{80}{13} \approx 6.2$$You flop a set of sevens on \(\text{K}♣\text{7}♥\text{3}♦\). SPR 6 with a set — you want to get stacks in over 2–3 streets. Bet flop, barrel turn, shove river (or get check-raised on any street and call). Sets are the ideal SPR 6 hand — strong enough to commit, with implied odds from opponents with top pair.
Example C: SPR 15 with TPTK Facing Check-Raise
Deep-stacked game. Pot = $30. Effective stacks = $450.
$$\text{SPR} = \frac{450}{30} = 15$$You hold \(\text{A}♦\text{K}♣\) on \(\text{K}♠\text{9}♥\text{4}♦\). You bet $20, villain check-raises to $80. Calling means committing to a pot where you will likely face two more large bets. Total stacks at risk = $450, pot after calling = $190.
At SPR 15, TPTK is not strong enough to happily stack off. A check-raise at this SPR heavily represents sets and two pair. Consider folding or calling one street only, looking to reassess. The depth punishes weak top pair massively.
🎲 SPR in Preflop Planning
Skilled players manipulate SPR preflop to create favorable conditions for their hand type. The key lever is bet sizing:
- 3-betting larger with big pairs (AA, KK) creates a lower SPR on the flop, making it easier to commit — you do not want to play AA deep in a multi-way pot at SPR 20.
- Calling instead of 3-betting with speculative hands (small pairs, suited connectors) preserves deep stacks, keeping SPR high and implied odds intact.
- Isolating from the blinds with a larger sizing vs. limpers creates a lower SPR, which helps strong top-pair hands and hurts drawing hands.
Example: With AA 200BB deep, consider 4-betting larger (or shoving pre-flop in tournaments) to avoid deep-SPR post-flop situations where your hand can be outdrawn cheaply.
$$\text{Target SPR for AA} \approx 2\text{–}4 \quad \text{(flop commitment comfortable)}$$ $$\text{Target SPR for 55} \approx 10\text{+} \quad \text{(set mining with implied odds)}$$💡 Practical Usage
Calculate SPR quickly using this two-step mental process:
- Note the pot size on the flop (add up all preflop action).
- Divide the effective stack by the pot. Round to the nearest whole number.
Then use the following mental anchors:
- SPR ≤ 4: Top pair is a commitment hand. Bet/call off.
- SPR 5–10: Need two pair or better to feel completely comfortable stacking off.
- SPR 10+: Need sets or stronger. Play carefully with one-pair hands.