Printed on every blackjack felt, in letters most players never read, is one of the most consequential sentences in the casino: either "Dealer stands on all 17s" or "Dealer must hit soft 17". The difference looks like trivia. It is actually a fifth of a percent of house edge and a handful of changed strategy plays, which makes it the second most important thing on the felt after the blackjack payout.
What the rule actually means
A soft 17 is a hand containing an ace counted as 11: ace-six, ace-two-four, ace-ace-five. The "soft" part means one card cannot bust it, because the ace can drop to counting 1. The dealer's script handles every other total identically at every table: hit 16 and below, stand on hard 17 and up. Soft 17 is the one hand where casinos split into two camps.
At an S17 table, the dealer's ace-six is finished business: a made, mediocre 17. At an H17 table, the dealer must draw again, and keeps drawing until reaching hard 17 or better, a soft 18 or better, or busting.
Why the redraw helps the house
Intuition says forcing the dealer to hit a made hand should be good for you; sometimes the dealer busts, after all. The intuition fails because a soft 17 is a poor made hand. Standing on it, the dealer can never beat your 18 through 21; the hand only pushes 17s and beats stiffs the dealer would have beaten anyway.
The redraw changes that. The dealer cannot bust a soft hand with one card, and a meaningful share of redraws land on 18, 19, 20 or 21, hands that now beat players who would have pushed or won against the frozen 17. The extra busts are real but cheaper than the upgrades are expensive. Net effect, per the commonly published tables: H17 raises the house edge by roughly 0.2 percentage points, about two dollars of expectation per thousand wagered. In a game whose whole edge is around half a percent with perfect play, as our house edge guide explains, that one sentence on the felt moves the price by nearly half.
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The plays that change
The rule also flips a small set of basic strategy cells, concentrated where you face a dealer ace, because the ace's dangerous redraws are exactly what H17 amplifies. In typical multi-deck games, the commonly published H17 charts differ from S17 mainly like this:
- Double 11 against an ace (S17 charts just hit it).
- A couple of extra soft doubles, most famously soft 19 against a 6, and soft 18 against a 2.
- Extra late surrenders against the ace where the option exists, including hard 17 against an ace, a play that exists in no S17 chart.
The exact list depends on deck count and the other rules, which is the standing lesson of our chart-reading guide: a chart is computed for a rule set, and memorizing one for the wrong game means confidently repeating small mistakes. A trainer that redraws its chart when you toggle the rule, as 21 Trainer does, makes the difference visible instead of theoretical.
Spotting it, and weighing it
Reading the felt takes five seconds. "Dealer stands on all 17s" is the good sentence; "Dealer must hit soft 17" is the surcharge. In practice, H17 has spread widely across American casinos, and S17 often survives at higher-minimum tables, so the choice is sometimes between rule quality and stakes.
Weigh it together with the payout line: a 3:2 S17 table is the classic good game, while a 6:5 payout costs roughly seven times what H17 does and overwhelms everything else on the felt. Rules stack, and knowing the stack is the cheapest edge-trimming a player ever gets: it costs nothing but attention.
Finally, train for the game you will actually face. If your local rooms deal H17, drill against an H17 chart, so the changed plays, the 11 against an ace especially, arrive as reflexes rather than trivia. If you split time between rule sets, practice both and let your accuracy stats tell you which chart's exceptions still slip. The rule is fixed the moment you sit down; whether your strategy matches it is entirely up to your preparation.
Frequently asked questions
What does S17 and H17 mean in blackjack?
They describe what the dealer must do holding a soft 17, a hand like ace-six where the ace counts as 11. At an S17 table the dealer stands on it; at an H17 table the dealer must hit it. The rule is printed on the table felt, usually as "Dealer stands on all 17s" or "Dealer must hit soft 17".
Is S17 or H17 better for the player?
S17 is better for you. When the dealer must hit soft 17, the redraw busts the dealer a little more often but upgrades the hand to 18 through 21 more often still, and the net effect raises the house edge by roughly 0.2 percentage points per the commonly published tables. All else equal, always prefer the table where the dealer stands on all 17s.
Does basic strategy change between S17 and H17?
Yes, in a handful of cells, mostly against a dealer ace. In typical multi-deck H17 games the commonly published charts double 11 against an ace and add a couple of soft doubles such as soft 19 against a 6, and where late surrender is offered they surrender an extra hand or two against the ace. A chart or trainer computed for your exact rules shows the precise set.
Why do casinos use H17 if it looks worse for them on soft 17?
Because it is not worse for them; the extra bust risk is a red herring. The redraw turns a mediocre forced 17, which can only push or lose against made hands, into 18 through 21 often enough to more than pay for the busts. H17 quietly earns the house roughly two extra dollars per thousand wagered, which is why it has spread.
How do I know if my table is S17 or H17?
Read the felt. The rule is printed on the table itself: "Dealer stands on all 17s" means S17, "Dealer must hit soft 17" means H17. It takes five seconds and, together with checking that blackjack pays 3:2, is the highest-value table inspection a player can make.