H17 vs S17: dealer hits or stands on soft 17

The soft-17 rule decides what the dealer does with a hand such as ace-six. Under S17 the dealer stands; under H17 the dealer must take another card. H17 is worse for the player by about 0.22 percentage points of house edge, and it flips a small, specific set of basic-strategy decisions, all of them towards more aggressive play.

What soft 17 is and why the rule exists

A soft hand contains an ace counted as 11. Ace-six is soft 17; ace-two-four is soft 17; ten-seven is hard 17. Hard 17 is always a stand for the dealer under either rule. The rule only concerns soft 17, which has a property no hard total has: the next card cannot bust it. A dealer who hits ace-six can finish anywhere from a hard 12 (after a five) to 21 (after a four), and may then be required to hit again.

Casinos adopted H17 because it favours them. A dealer standing on soft 17 loses to every player 18 or better and only pushes a 17. A dealer who hits it busts more often but also reaches 18 through 21 more often, and the second effect is larger. Wizard of Odds’ dealer-outcome tables illustrate the trade: the dealer’s overall bust rate rises by only about 0.3 percentage points under H17, while a large share of what used to be a final 17 becomes a stronger total.

The cost in house edge

Wizard of Odds measures H17 at −0.22% to the player’s expected return against its eight-deck S17 baseline; Wikipedia and BlackjackInfo quote the same magnitude. The combinatorial figures in Wizard of Odds’ Appendix 9 show it directly for six decks (resplit to four hands, no drawing to split aces):

In money terms, a $10 flat bettor playing 80 hands an hour gives up an extra 80 × $10 × 0.0022 = $1.76 per hour at an H17 table. That is a small sum per session and a large one over a year, which is why the rule matters more to regular players than to tourists. It also compounds with other restrictions: the table in how rule variations change the house edge shows that H17 plus 6:5 payouts turns a 0.40% game into one above 2%.

Which basic-strategy cells flip

Because the dealer’s weak soft 17s become stronger totals under H17, the player should press harder in a few borderline spots and give up a few hands that were just worth playing out. Wizard of Odds lists six changes for its four-to-eight-deck chart when moving from S17 to H17:

Everything else in the multi-deck chart is identical. The surrender rows only apply where late surrender is offered; the site’s training profile (six decks, S17, DAS, no surrender) uses the left-hand column throughout, and the strategy chart reflects that.

The expected values behind the flips

The decisions above are close calls, which is why a rule change at the dealer’s end moves them. Wizard of Odds’ Appendix 9 gives the expected value of each option per unit staked, for six decks, double after split, resplit to four hands. Positive numbers are player gains; −0.5 is the value of surrender.

Read each pair against the other. Under S17, hitting 11 against an ace beats doubling by nearly two cents per unit; under H17 both options lose value because the dealer’s ace finishes stronger, but hitting loses more, and doubling moves ahead by one and a half cents. The soft-18 and soft-19 doubles are the same story against small upcards: when the dealer’s ace-six can no longer stand on 17, standing on 18 or 19 is worth less, and taking one card for double stakes becomes the better of two slightly worse options.

The surrender rows follow a simple threshold. Surrender returns exactly −0.5 per unit. Hitting 15 against an ace returns −0.483 under S17, better than surrender, and −0.510 under H17, worse. Standing on 17 against an ace returns −0.476 under S17 and −0.514 under H17. Both hands cross the −0.5 line when the rule changes. Every one of these plays is available as a worked page under hands, stated for the training profile.

How much a wrong chart costs

Playing the S17 chart at an H17 table, or the reverse, costs very little, because every flipped cell is a near tie. The six hands above account for a small fraction of all hands dealt, and the EV gap in each is between 0.003 and 0.04 per unit. Wizard of Odds describes its S17 chart as “fine under any set of rules” and presents the H17 modifications as refinements for perfectionists. Learn one chart well; add the H17 cells once the rest is automatic, which is what the trainer is for.

What does cost money is confusing hard and soft totals. A dealer showing ace-six under H17 must hit; a player holding ace-six faces a different question entirely and should consult the soft hands guide. The 0.22-point cost of H17 is a fact about the dealer’s procedure, not a reason to change how you play soft 17 yourself.

Reading the rule at the table

The soft-17 rule is printed on the felt in nearly every casino, usually in the arc above the betting spots: “Dealer must stand on all 17s” or “Dealer must draw to 16 and stand on all 17s” means S17; “Dealer must hit soft 17” means H17. In a European no-hole-card game the sentence may be on a placard instead. The rule is independent of deck count, payout and doubling rules, so check it separately. The choosing a table guide lists it as the second item to read after the blackjack payout, and that ordering is correct: 6:5 costs six times as much as H17, but H17 is the one that changes how you play.

Related reading

• How rule variations change the house edge
• Basic strategy
• Surrender
• Soft hands