Open-Ended Straight Draw Odds: 8 Outs Math

Flop → River

31.45%

Turn Card

17.02%

River Card

17.39%

Flop check-raise — strong semi-bluff

Check-raising flop OESDs creates fold equity against weak made hands. Even if villain calls, you have 31.5% to hit by river plus implied odds when you do.

Donk lead the flop

Leading 1/3 pot OOP with an OESD on dynamic boards exploits passive opponents. Folds happen often; calls give you a price for free turn-river cards.

Turn float into river barrel

Calling a flop c-bet with an OESD and barreling river even when missed targets capped ranges. Use board cards that scare top-pair holdings.

All-in shove with combo draw

OESD + flush draw (15 outs, 54%) plays as a near-coin-flip vs top pair. Shoving for stacks with this combo is +EV on most board textures.

What are the odds of hitting an open-ended straight draw?

An OESD has 8 outs and the flop-to-river probability of completing it is 31.45%. The Rule of 4 & 2 estimates 8 × 4 = 32%, within 0.6 percentage points of the exact figure. On the turn alone, the OESD hits 17.02%; on the river alone, 17.39%. These probabilities make the OESD one of the strongest single-shape draws in Texas Hold'em.

How many outs does an OESD have?

An open-ended straight draw has 8 outs. Two ranks complete the straight — one on each end. For example, holding T-9 on a flop of 8-7-2, you need a J (4 jacks in deck) or a 6 (4 sixes in deck) to make a 5-card straight. 4 + 4 = 8 outs. The Rule of 4 & 2 gives 8 × 4 = 32%, close to the exact 31.45%.

What pot odds do I need to call with an OESD?

With two cards to come, you need at least 2.18-to-1 pot odds (31.45% equity) to call profitably with a pure OESD. Calling on the turn deciding turn-only requires 4.75-to-1 (17.4%). Most realistic bet sizes give favorable pot odds: a half-pot bet offers 3-to-1, which is sufficient for an OESD when implied odds and any backdoor draws are factored in.

Is an OESD a good draw?

Yes — the OESD is one of the strongest non-combo draws. With 31.5% equity flop-to-river, it can profitably call up to 1/2 pot bets and is a standard semi-bluff hand. When combined with a flush draw, it becomes a 15-out combo draw (54.1% equity) — a favorite over most made hands. Skilled players raise OESDs frequently for fold equity plus pot building.

What is the difference between an OESD and a double gutshot?

Both have 8 outs and 31.45% equity flop-to-river, so mathematically they are equivalent. The difference is structure: an OESD has two adjacent ranks needed (one on each end of the straight), while a double gutshot has two separate inside cards needed. Example: 6-9 on 5-7-8 is a double gutshot (need a 6 or 9 wait — that's actually two separate gutshots to two straights). In play, both behave identically.

Should I semi-bluff with an OESD?

Yes — the OESD is one of the most common semi-bluff hands in poker. With 31.5% equity when called and ~30-50% fold equity on most boards, semi-bluffing is strongly +EV. The math: if you bet 1/2 pot and villain folds 40% of the time, the EV is approximately 0.4 × pot + 0.6 × (0.315 × 1.5 pot − 0.685 × 0.5 pot) ≈ +0.45 pot per attempt.

How do you identify an OESD on the flop?

Look for two ranks adjacent to your hole cards that, with the board, would form a 5-card straight on either end. Example: hole cards T-9, flop 8-7-2 — you have 6-7-8-9-T straight if a 6 comes (low end) and 7-8-9-T-J if a J comes (high end). That is open-ended. A gutshot has only one rank completing the straight (in the middle).