Flopping a Straight in Texas Hold'em — Exact Probability

Interior Connectors

1.31%

1 in 76

One-Gappers

0.99%

1 in 101

Two-Gappers

0.55%

1 in 182

OESD (8 outs)

10.5%

1 in 9.5

Peak (4 straights)

54, 65, 76, 87, 98, T9, JT

1.31%

Maximum straight potential. All 7 interior connectors sit in 4 possible 5-card runs simultaneously. Best speculative hands for stack-deep play.

Strong (3 straights)

43, 54 edge, QJ, KQ

~1.05%

Three straight-making runs. One direction is capped by deck edge. Still premium; slightly less raw straight equity than peak connectors.

Moderate (2 straights)

One-gappers (53, 75, T8, J9)

0.99%

Three usable straight runs despite the gap. One-gappers remain playable — gutshot draws are more common than straights, but equity adds up.

Weak (1–2 straights)

Two-gappers (52, 64, T7)

0.55%

Only 2 possible straights. Requires deep stacks and good position. Two-gappers are speculative hands that rely on other value beyond straight draws.

What are the odds of flopping a straight with connectors?

1.31% for interior connectors (54s through JTs, offsuit or suited) — approximately 1 in 76 flops. This is calculated from the 4 possible 5-card straights that include both hole cards for a middle connector like 87: {4-5-6-7-8}, {5-6-7-8-9}, {6-7-8-9-T}, {7-8-9-T-J}. Each requires a specific 3-card flop combination, and C(remaining-cards, 3) for each flop gives the 1.31% total. Edge connectors like KQ or A2 drop to ~0.98% because fewer straight combinations are available.

What about one-gappers and two-gappers?

One-gappers (e.g., 75, T8, J9) flop a straight 0.99% (1 in 101). Two-gappers (e.g., 74, J8, T7) flop a straight 0.55% (1 in 182). The rank gap reduces the number of 5-card straight combinations that can include both hole cards. A connector sits in the middle of 4 different 5-card runs; a one-gapper sits in 3; a two-gapper in 2. Three-gappers (e.g., K9, T6) sit in approximately 1 run and flop straights around 0.10% of the time.

How often do connectors flop an open-ended straight draw (OESD)?

10.5% — about 1 in 9.5 flops. An OESD has 8 outs and approximately 31.5% equity to complete by the river. Combined, connectors connect with the flop for some straight equity (made straight + OESD + gutshot) over 28% of the time — which is a primary reason they are profitable at deep stacks despite rarely flopping complete straights.

Are suited connectors better than offsuit for flopping straights?

Identical probability for straight-related outcomes — suit has no effect on straight combinations. Suited connectors gain on top of their straight equity: the 0.84% flush-flopping rate, 10.9% flush draw rate, and occasional combo draws (OESD + flush draw simultaneously). The combination makes suited connectors the most flexible speculative hands, but for straights specifically, 87o and 87s are equivalent.

What is the probability of flopping a straight from any random two cards?

Approximately 0.45% when averaged across all possible hole card combinations. This includes the many disconnected hands (K3, J4, T2, etc.) that have near-zero straight-flopping probability. The 1.31% figure applies specifically to interior connectors. For disconnected hands, the probability drops to 0.04% (1-hole-card straights where the board has 4 connected cards) — which is rare and cannot be planned for.

Do I need specific pot odds to call with an OESD?

An OESD has 31.5% equity over two streets. You can profitably call any bet up to a three-quarter-pot bet (30% pot odds). Against a pot-sized bet (33.3% pot odds required), an OESD must fold on pure pot odds or rely on implied odds. On the turn with only one street remaining, OESD equity drops to 17% — meaning you now need pot odds below 17% to call, which translates to approximately a quarter-pot bet or smaller.

Why do connectors lose straight value at the deck edges?

A complete straight must contain 5 consecutive ranks. Middle connectors like 87 can sit inside 4 different 5-card runs: 4-5-6-7-8, 5-6-7-8-9, 6-7-8-9-T, 7-8-9-T-J. But A2 can only form one straight (A-2-3-4-5), and A-K only one (T-J-Q-K-A). The count: A2 = 1 straight, 32 = 2, 43 = 3, all from 54 through JT = 4, QJ = 4 (including Broadway), KQ = 3, AK = 1 (Broadway only). Peak straight value runs from 54 through T9 — all at 4 possible straights each.