H17 vs S17

What H17 and S17 Mean

S17 (stand on soft 17) and H17 (hit on soft 17) describe what the dealer must do when holding a hand like A-6. Under S17 rules, the dealer stands. Under H17 rules, the dealer must hit, giving them a chance to improve to 18-21 but also a chance to bust.

At first glance, you might think H17 is better for the player since the dealer might bust. But the math shows otherwise: when the dealer hits soft 17, they improve their hand more often than they bust. The net result is roughly a 0.2% increase in house edge under H17 rules compared to S17.

House Edge Impact

A 0.2% edge increase might sound small, but it is one of the largest single-rule impacts after the 3:2 vs 6:5 payout difference. Over 10,000 hands at $25 average bet, the H17 penalty costs an extra $50 compared to S17. Combined with other unfavorable rules, it can push a game from marginal to unplayable for counters.

How H17 Changes Your Strategy

The S17/H17 rule changes the correct basic strategy play on several specific hands. If you memorized strategy for an S17 game and play at an H17 table, you will make suboptimal decisions on these hands:

Key Strategy Differences (H17 vs S17)

Most changes involve doubling more aggressively against the dealer’s ace (because the dealer is more likely to bust or end with a weak hand) and surrendering more hands against the ace (because the dealer’s expected outcome improves under H17).

Impact on Card Counters

For card counters, H17 has a more nuanced effect. The added dealer bust frequency on soft 17 can actually be slightly favorable at high true counts because more of the remaining cards are tens. However, this benefit is small and does not offset the base house edge increase.

Several Illustrious 18 deviations change their index numbers under H17 rules. If you count cards, make sure your deviation indices match the rules of the game you are playing. Using S17 indices at an H17 table (or vice versa) will cost you EV on deviation plays.

How to Identify S17 vs H17 at the Table

1. Check the table felt. Most casinos print "Dealer must stand on all 17s" (S17) or "Dealer hits soft 17" (H17) on the layout. Look near the insurance line.
2. Read the placard. The min/max bet sign sometimes lists this rule.
3. Ask the dealer. Simply ask: "Do you hit or stand on soft 17?" Dealers answer this question hundreds of times and will not find it unusual.
4. Watch the action. If the dealer draws on A-6, the table is H17.

Table Selection: Putting It All Together

When choosing a table, evaluate rules in this priority order. Each row shows the approximate house edge impact:

Ideally, look for a 3:2 / S17 / DAS / surrender game. These are less common than they used to be, but they exist. For counters, penetration quality matters more than some of these rule differences — see the shoe penetration guide.

Frequently Asked Questions

Is H17 always worse for the player?

Yes, in terms of house edge. The additional dealer bust frequency does not compensate for the times the dealer improves from soft 17 to a higher total. The net result is always ~0.2% worse for the player.

Should I switch casinos to find S17?

If the S17 casino has similar minimums and penetration, yes. A 0.2% edge improvement over thousands of hands adds up significantly. For casual players, it matters less but is still worth choosing when both options are convenient.

Does H17 affect Illustrious 18 index numbers?

Yes. Several deviation indices shift by 1-2 true count points under H17 vs S17. Use indices matched to the game you are playing. The Blackjack 3000 deviation trainer lets you select your rule set so the practice matches your target game.

Related Guides

• 3:2 vs 6:5 rules
• Basic strategy chart
• Risk of ruin calculator
• Shoe penetration
• Illustrious 18 deviations