A straight flush is a poker hand in which the required cards are consecutive in rank and all belong to the same suit. In standard five-card high poker, 5♣-6♣-7♣-8♣-9♣ is a straight flush because the ranks form an unbroken sequence and every card is a club.
Both conditions matter. 5♣-6♦-7♣-8♣-9♣ is a straight but not a flush. 2♥-5♥-8♥-J♥-K♥ is a flush but not a straight. 6♠-7♠-8♠-9♠-J♠ has one suit but misses the 10, so it is not a straight flush.
The hand name can describe different card counts
“Straight flush” is a category, not a promise that every casino game uses five cards. Standard draw poker and video poker normally evaluate five-card hands, but casino variants can define three-card, four-card, five-card, or even longer qualifying combinations.
That is why the first question should always be: what does this game’s rule sheet mean by straight flush? A three-card blackjack side bet may pay a three-card straight flush. Four Card Poker evaluates four-card categories. Pai gow or progressive products can define different qualifying structures again.
The words remain the same because the underlying idea remains the same—sequence plus suit—but hand length and payout belong to the specific game.
The royal flush is structurally the highest five-card straight flush
In conventional five-card high poker, 10-J-Q-K-A in one suit is an ace-high straight flush. It is commonly called a royal flush and is often shown as a separate paytable category because casinos and video poker machines award it much more than an ordinary straight flush.
That creates two valid uses of the term:
- in hand-ranking theory, a royal flush is the highest straight flush;
- in a paytable, “straight flush” may mean only the non-royal straight flushes because the royal has its own line.
The distinction is especially important in video poker. A paytable that lists “Royal Flush” and “Straight Flush” is not counting the same hand twice. The royal is removed from the ordinary straight-flush payout category and receives its own award.
See royal flush and paytable for those two concepts separately.
Ace can be high or low, but it does not wrap around
Under common five-card high-poker rules, ace can sit above king in 10-J-Q-K-A or below 2 in A-2-3-4-5. A suited A-2-3-4-5 is therefore a five-high straight flush, often nicknamed a steel wheel.
Ace does not normally connect the two ends at once. Q-K-A-2-3 is not a straight. K-A-2-3-4 is not a straight. The ace is high or low for the sequence; it is not a circular bridge through the deck.
A specialized game can define another ranking, but that exception must come from the game’s rules rather than from ordinary poker convention.
There are 40 five-card straight flushes in a 52-card deck if royals are included
A standard deck provides ten possible five-card sequences:
- A-2-3-4-5
- 2-3-4-5-6
- 3-4-5-6-7
- 4-5-6-7-8
- 5-6-7-8-9
- 6-7-8-9-10
- 7-8-9-10-J
- 8-9-10-J-Q
- 9-10-J-Q-K
- 10-J-Q-K-A
Each sequence can occur in four suits, so:
10 sequences × 4 suits = 40 straight flushes
The number of unordered five-card hands from 52 cards is:
C(52,5) = 2,598,960
Therefore:
P(any straight flush, including royal) = 40 / 2,598,960
which is approximately 0.001539%, or about 1 in 64,974 random five-card hands.
If a paytable treats the four royals separately, the ordinary non-royal category contains 36 combinations:
36 / 2,598,960 ≈ 0.001385%
or about 1 in 72,193 fresh five-card deals.
These numbers describe a random five-card hand dealt from a full deck. They are not the final frequency of straight flushes in strategically played video poker, because a video poker player keeps some cards and replaces others.
Four to a straight flush is a draw, not a completed hand
Suppose a video poker player is dealt 5♠-6♠-7♠-8♠ plus an unrelated card. Holding the four suited consecutive cards leaves 47 unseen cards. The 4♠ or 9♠ completes a straight flush, so the direct completion probability is:
2 / 47 ≈ 4.255%
An edge draw can have only one direct straight-flush completion. Holding A♦-2♦-3♦-4♦, for example, needs the 5♦:
1 / 47 ≈ 2.128%
Those figures do not prove that holding four to the straight flush is the optimal video poker decision in every hand. The complete EV also includes ordinary straights, flushes, pairs, high-card value, royal possibilities, discarded-card effects, and the exact paytable. A video poker strategy chart or video poker analyzer compares the full set of possible draws.
Open-ended and inside-looking patterns can be deceptive
Players often see “four suited cards close together” and mentally group them as equivalent. They are not.
5♠-6♠-7♠-8♠ is open-ended: both 4♠ and 9♠ complete the straight flush. 5♠-6♠-8♠-9♠ has an internal gap and only 7♠ completes the exact five-card straight flush. A holding such as 2♠-3♠-4♠-5♠ is also effectively one-ended because ace or 6 can make a straight, but only A♠ or 6♠ can make suited sequences—and the paytable and other outcomes determine the better hold.
The number of direct completions is therefore a property of the specific ranks held, not merely the phrase “four to a straight flush.”
Wild cards can create a qualifying straight flush without changing the natural definition
In Deuces Wild, Joker Poker, or other wild-card games, a wild card can substitute for a missing rank and suit if the rules allow it. A hand such as 5♥-6♥-7♥-8♥-2♣ can be evaluated as a straight flush when the deuce is wild and stands for 4♥ or 9♥.
The paytable decides whether natural and wild straight flushes are combined. Some games separate a natural royal from a wild royal but keep ordinary straight flushes together. Others create additional categories.
This is why wild royal and five of a kind are separate glossary concepts. Wild-card games change the set of reachable hands and their payouts; they do not change what “sequence plus suit” means.
Comparing two straight flushes normally uses the highest card in the sequence
When two same-length straight flushes are compared under ordinary high-poker ranking, the one with the higher top rank wins. A 9-high straight flush beats an 8-high straight flush. The A-2-3-4-5 wheel is five-high, so it loses to 2-3-4-5-6.
Suits generally do not break equal poker hands. If two players use the same five community cards to make an identical straight flush, a conventional poker pot is split rather than awarded by suit.
A casino bonus wager can settle differently because it may not compare player hands at all. A side bet can simply pay a posted amount whenever the player’s cards meet the qualifying definition. Hand ranking and wager settlement are separate questions.
Straight flush probability changes immediately when the game changes the card set
The 1-in-64,974 figure is specific to a fresh five-card hand from one standard 52-card deck. Add jokers, use multiple decks, remove cards, change hand length, or condition the hand on known cards and the probability changes.
For example, a three-card straight flush in a single deck has many more qualifying combinations relative to the number of three-card hands than a five-card straight flush does relative to five-card hands. That is one reason three-card side bets can offer straight-flush awards without requiring astronomically large payouts.
Players should therefore avoid importing a familiar “poker odds” number into a different game format.
Official rule sheets are the final authority on the category used at a table
Massachusetts Gaming Commission’s published poker rules define a five-card straight flush as same-suit cards in consecutive ranking and also show how regulated rules specify hand categories rather than leaving them to table folklore. Other approved games can define shorter straight-flush categories in their own rule sheets.
For glossary purposes, the safest definition is: a straight flush combines the required consecutive ranks with one suit; the game determines how many cards are required, how ace and wild cards are treated, and what the hand pays.
For neighboring hand types, compare straight, flush, full house, and royal flush.