Blackjack Strategy Trainer 21
What "soft 17" actually means
A hand is "soft" when it contains an Ace counted as 11 without busting. A soft 17 is any hand totaling 17 where one of those points is a flexible Ace. The textbook example is A,6 — but A,A,5 and A,2,4 are also soft 17s. The defining property is that the Ace can drop to 1 if the next card would push the total over 21, so the hand cannot bust on a single hit.
That flexibility is precisely why the soft 17 rule matters. A hard 17 is a dead hand for the dealer — drawing would risk a bust on most cards. A soft 17 carries no such risk on the next card, which is why some casinos let dealers keep drawing on it.
The two house rules: S17 and H17
Every blackjack table commits to one of two procedures for soft 17:
- S17 — Dealer Stands on all 17s, soft or hard. Better for the player.
- H17 — Dealer Hits soft 17 and stands only once the hand becomes hard 17 or higher. Worse for the player.
The rule is printed on the felt or on a sign at the table: "Dealer stands on all 17s" or "Dealer hits soft 17." If you can't see it, ask the dealer — they will tell you.
Why H17 is worse for the player
When the dealer is forced to stand on soft 17, a player holding 18, 19, or 20 wins that round. When the dealer can hit it, that soft 17 has roughly a 50% chance of improving to 18, 19, 20, or 21. The dealer trades a guaranteed 17 for a distribution that pushes more of your 18s, beats more of your borderline 17-totals (via a 21), and still busts some of the time.
The math nets out to roughly +0.22% to the house edge under H17 versus S17, all other rules equal. That number is small per hand and brutal per session: across 80 hands an hour at $25 a hand, the H17 surcharge alone costs about $4.40/hour in expectation.
House edge comparison
The soft 17 rule never travels alone — deck count, double-after-split (DAS), and surrender all interact. Here's how some common rule combinations stack up, assuming basic strategy played perfectly and 3:2 blackjack payouts:
| Game | Soft 17 | House edge |
|---|---|---|
| 2-deck, DAS, late surrender | S17 | ~0.19% |
| 6-deck, DAS, late surrender | S17 | ~0.43% |
| 6-deck, DAS, late surrender | H17 | ~0.65% |
| 8-deck, DAS, no surrender | H17 | ~0.72% |
A 6-deck S17 game with surrender is roughly the cleanest mainstream shoe game you'll find at $10–$25 tables. The same shoe under H17 erases most of the surrender benefit.
Where you'll find each rule
Geography matters more than people expect:
- S17 — Dominant on the Las Vegas Strip's higher-limit tables ($25+ pits), most California card rooms with shoe games, and many European casinos.
- H17 — Standard on downtown Vegas, low-limit Strip tables ($5–$15), much of Atlantic City historically, the bulk of riverboat and tribal casinos in the US, and a large share of online and live-dealer blackjack variants.
The general pattern: the cheaper the table, the more likely it hits soft 17. Casinos use H17 (and 6:5 payouts) to compensate for a lower minimum.
The six strategy cells that change under H17
Basic strategy is computed from the dealer's exact rule set. Switch S17 to H17 and a small but important handful of decisions flip. These are the only cells worth memorizing as "H17 differences":
| Your hand | Dealer up | S17 play | H17 play |
|---|---|---|---|
| A,7 (soft 18) | 2 | Stand | Ds |
| A,8 (soft 19) | 6 | Stand | Ds |
| 11 | A | Hit | Double |
| 8,8 | A | Split | Surrender / else Split |
| 15 | A | Hit | Surrender / else Hit |
| 17 | A | Stand | Surrender / else Stand |
"Ds" means double if doubling is allowed on that hand, otherwise stand. The surrender lines assume late surrender is on offer; if it isn't, fall back to the second option.
Reading the changes
Three of the six changes happen when the dealer shows an Ace. That isn't coincidence: H17 makes the dealer's Ace meaningfully stronger because so many of those underlying soft hands now have a second chance to improve. Doubling 11 and surrendering 15 and 17 both fall out of that.
The A,7 vs 2 and A,8 vs 6 doubles are the ones casual players miss. They feel aggressive — you're doubling on a hand that already wins under S17. Under H17, the dealer pulls more 18s out of their soft 17, which turns your push on 18 into a loss. Doubling for value (when allowed) extracts the edge before that happens.
NOTE
If you only play one rule set, learn the chart for your rule set — don't try to hold both in your head at once. The H17-difference cells above are exactly what you'd add to an S17 chart to convert it, and exactly what you'd remove going the other direction.
How to identify the rule before you sit down
- Check the felt. The rule is printed in the betting area or on a placard. "Dealer stands on all 17s" = S17. "Dealer hits soft 17" or "Dealer must hit soft 17" = H17.
- Check the payout in the same breath. 3:2 blackjack pays $15 on a $10 bet; 6:5 pays $12. 6:5 adds roughly +1.4% to the house edge — far more than the H17 rule. Walk past 6:5 tables even if they're S17.
- Ask the dealer. Dealers will answer rules questions before you bet. Ask about soft 17, surrender, doubling after split, and re-splitting Aces.
Should you avoid H17 tables?
If an S17 table with otherwise identical rules and minimums is available, sit there. The +0.22% is free EV.
In practice the choice is rarely that clean. A typical question is "$10 H17 with DAS and surrender, or $25 S17 with DAS but no surrender?" Run the numbers: the surrender benefit under late surrender is about +0.07%, the H17 cost is +0.22%, so the rules-only swing is ~+0.15% in favor of the S17 table. But you'd be betting 2.5x as much. Stick with the H17 table at the lower minimum — bankroll variance beats a 0.15% edge tweak.
The hierarchy of what matters, from biggest impact to smallest:
- Blackjack payout (3:2 vs 6:5): ~+1.4% if 6:5
- Number of decks (single → eight): up to ~+0.55%
- Soft 17 (S17 → H17): +0.22%
- Surrender available: −0.07%
- Double after split allowed: −0.14%
- Re-split Aces allowed: −0.08%
Soft 17 sits in the middle. Worth fighting for when other rules tie; not worth giving up a better game over.
ENHC and H17 — a double penalty
European No-Hole-Card (ENHC) games don't deal the dealer a hole card until players have finished acting. If the dealer ends up with a blackjack, your splits and doubles lose in full (rather than just the original bet). ENHC alone costs ~+0.11% in house edge. Combine ENHC with H17 and you have one of the worst common rule combinations outside of 6:5: ~0.77% on a 6-deck shoe before any payout penalty. Many online live-dealer tables run exactly this combination.
Counter-strategy: don't double or split into a dealer Ace under ENHC (the chart adjusts), and treat 10 vs 10 and 11 vs 10 more conservatively.
Practice both rule sets
The fastest way to internalize the H17 differences is to drill the six cells against an active opponent until they're automatic. Blackjack Strategy Trainer 21 lets you toggle between S17 and H17 in settings, so you can train both rule sets and feel the strategy flip in your hands rather than reading about it on a chart.
Train S17 and H17 with spaced repetition
The free Android app drills basic strategy under both soft 17 rules, surfaces the cells you get wrong most, and reinforces them until they're automatic.