A straight flush represents one of the rarest and strongest hands you can make in a game of poker.
The straight flush marks the second-best possible hand according to the standard poker hand rankings. Only a royal flush outranks the straight flush in terms of 5-card poker hands.
Whether you’re playing Texas Hold’em, Omaha, or another poker variant, a straight flush is hard to make. Let’s dive into some poker probabilities and take a look at just how rare of an occurrence a straight flush is in a poker game.
What is a Straight Flush?
A straight flush is a five-card poker hand that includes both a straight and a flush. The only way to make a straight flush is to put together five cards of the same suit, with those five cards also ranking in sequential order (such as they do when you make a straight).
Examples of a straight flush include the following:
- K♠ Q♠ J♠ T♠ 9♠
- 7♦ 6♦ 5♦ 4♦ 3♦
- T♣ 9♣ 8♣ 7♣ 6♣
- 5♥ 4♥ 3♥ 2♥ A♥
The highest possible straight flush is the ace-high version (A♠ K♠ Q♠ J♠ T♠), and that specific hand is called a royal flush.
While the royal flush beats any other hand in the poker hand rankings, the straight flush beats four-of-a-kind, a full house, three-of-a-kind, and any other made hand.
In the case of two straight flushes going head-to-head, the high straight flush (the hand with the strongest high card) wins. For example, K♠ Q♠ J♠ T♠ 9♠ would beat J♠ T♠ 9♠ 8♠ 7♠.
The player with J♠ T♠ 9♠ 8♠ 7♠ would meet a case of almost unfathomable bad luck in that scenario. That’s because making any variety of straight flush is a monumental task in a game of poker.
Straight Flush Odds
The poker probability of drawing a straight flush varies depending on the poker variant you’re playing.
Before we dive into that, let’s first take a look at the odds of randomly making a straight flush when drawing five cards out of a 52-card deck.
From the regulation 52-card deck, there are nine distinct ways to make a straight flush (not counting the royal flush). For example, 5♥ 4♥ 3♥ 2♥ A♥ and 5♠ 4♠ 3♠ 2♠ A♠ are the same distinct hand, but with different suits (hearts and spades).
Each distinct straight flush comes in four suits, so the total number of ways to draw a straight flush is 36.
The total number of distinct hands you can draw from a 52-card deck is 2,598,960. We can calculate the poker probability of making a straight flush as (36/2,598,960).
That calculation equates to an 0.00139% chance of making a straight flush from five random cards, or 72,192-to-1 odds against. Let’s compare that to the odds of making other hands in the poker hand rankings:
- Royal Flush – 0.000154% (649,739-to-1 odds against)
- Straight Flush – 0.00139% (72,192-to-1)
- Four of a Kind – 0.02401% (4,164-to-1)
- Full House – 0.1441% (693-to-1)
- Flush – 0.1965% (509-to-1)
- Straight – 0.3925% (254-to-1)
- Three of a Kind – 2.1128% (46-to-1)
- Two Pair – 4.7539% (20-to-1)
- One Pair Hand – 42.2569% (1.37-to-1)
- High Card/No Pair – 50.1177% (roughly 1-to-1)
Straight Flush Odds in Texas Hold’em
In Texas Hold’em, the poker player is tasked with making the best possible 5-card poker hand out of seven total cards. You can use all possible card combinations from two hole cards and five community cards.
Texas Hold’em rules make it slightly more probable that you’ll make a straight flush.
Using any combination of your starting hand and the community cards, you have an 0.0279% chance of making a straight flush in Texas Hold’em. This translates as 3,590-to-1 odds against.
Playing a solid preflop strategy with suited connectors gives you the best chance of making a straight flush.
Any flop that gives you a straight flush possibility also yields straight draws and flush draws. While a straight flush is one of the strongest hands in poker, making a flush hand or a straight often gives you the best hand as well.
Here’s a look at how straight flush poker probabilities stack up against other hands in Texas Hold’em:
- Royal Flush – 0.0032% (30,939-to-1 odds against)
- Straight Flush – 0.0279% (3,590-to-1)
- Four of a Kind – 0.168% (594-to-1)
- Full House – 2.6% (37.5-to-1)
- Flush – 3.03% (32-to-1)
- Straight – 4.62% (21-to-1)
- Three of a Kind – 4.83% (20-to-1)
- Two Pair – 23.5% (3.25-to-1)
- One Pair Hand – 43.8% (1.3-to-1)
- High Card/No Pair – 17.4% (4.75-to-1)
Note that with the exception of high card/no pair hands, all made hands in the poker hand rankings happen more often in Texas Hold’em, or any poker variant that involves making the best five-card poker hand out of seven total cards.
If you play online poker, you’ll see straight flushes occur much more frequently than the slower-paced live version of poker. Whether it’s live or online poker, however, a straight flush is a significantly rare occurrence.