It's a Saturday night on the Vegas Strip. You sit down at a $25 blackjack table at a $5,000-bankroll session and play four hours. The table next to you looks identical — same felt, same shoe, same dealer uniform, same minimum. The only difference is one line of fine print on the layout: yours says 'Dealer must hit soft 17,' the table next to you says 'Dealer must stand on all 17s.' Over those four hours at 80 hands per hour, that one rule difference costs you about $1.76. Multiplied across the twelve sessions you'll play that year on your annual Vegas trip, it's about $21. Multiplied across a serious player's twenty-year career, it's a few thousand dollars — and it lives entirely in a rule most recreational players never read.
The H17 vs S17 distinction is the second-most-impactful rule on the blackjack felt after the BJ payout, and unlike the 6:5 payout it doesn't announce itself with bold red text. It's printed in three-millimeter type in the corner of the layout, and most players don't even know to look. This post is the full math, the strategy deltas that move with it, and how to read a table fast enough to walk past the bad one.
What the rule actually means
A soft 17 is any 17 that contains an Ace counted as 11 — A,6 is the canonical example, but A,2,4 and A,3,3 are also soft 17s. The 'soft' part means the dealer can't bust by taking another card (the Ace flips down to 1). The rule choice is whether the dealer hits or stands on that specific total.
S17 (Stand on Soft 17, sometimes called 'Dealer stands on all 17s') means the dealer freezes at 17 regardless of whether the hand is soft or hard. H17 (Hit Soft 17) means the dealer continues drawing on a soft 17, hoping to land on 18-21. Hard 17 is always a stand under both rules.
On its face, H17 looks like a worse outcome for the dealer — the house is voluntarily giving up a 17 to try for more. But the math runs the other way: hitting soft 17 gives the dealer one more drawing card, and the expected outcome of that extra card is higher than a frozen 17. The dealer pushes more pushable hands (you also have 17, dealer also lands 17 = push under S17, but under H17 the dealer often beats your 17 by landing 18-21). The net is roughly 0.22% in the casino's favor.
The honest number from the trainer
TableSharp's EV calculator uses the canonical Wizard of Odds reference numbers. Off a 6-deck S17 DAS no-surrender 3:2-blackjack baseline of 0.50% house edge, the adjustments stack like this:
- Base 6D S17 DAS no-LS 3:2 BJ: 0.50% house edge
- H17 instead of S17: +0.22%, bringing the edge to 0.72%
- DAS off: +0.14%
- LS allowed: -0.07%
- 6:5 BJ: +1.39% (the killer, covered in its own post)
0.22% is small in isolation. It looks like noise next to the 1.39% catastrophe of a 6:5 payout. But it compounds with the rest of your rule set — and it changes the strategy chart in eight specific cells, which means a player drilled on the wrong chart leaks slightly more than the raw 0.22% suggests.
What 0.22% costs in real dollars
House edge times bet times hands gives you expected hourly loss. At a typical 80 hands per hour shoe pace:
- $10/hand: 80 × $10 × 0.0022 = $1.76/hr extra. Over a 4-hour session: $7.04.
- $25/hand: 80 × $25 × 0.0022 = $4.40/hr extra. Over a 4-hour session: $17.60.
- $50/hand: $8.80/hr extra. 4-hour session: $35.20.
- $100/hand: $17.60/hr extra. 4-hour session: $70.40.
Multiplied across a year of casual Vegas play (say six trips, four hours each) at $25/hand: about $106 of pure rule cost. Across a serious player's twenty-year career at the same volume: about $2,100. None of that is variance, none of it is bad play — it's the cost of the dealer's extra card on soft 17, paid silently by every player at the table who hasn't read the layout.
The eight cells that move
H17 doesn't just shift your edge — it shifts the chart. There are eight basic-strategy cells where the H17 answer differs from the S17 answer. Players drilled on an S17 chart who walk into an H17 table mis-play these eight cells until they re-learn.
- A,7 (soft 18) vs dealer 2: S17 says stand. H17 says Ds (double if allowed, else stand). The H17 dealer is more likely to land 18-21 from a 2 upcard than the S17 dealer, so you push the bet.
- A,8 (soft 19) vs dealer 6: S17 says stand. H17 says Ds. Same logic — you double a soft 19 against a 6 only when the dealer is hitting soft 17.
- 11 vs dealer Ace: S17 says hit. H17 says double. Against an H17 dealer's Ace, doubling 11 is now correct because the dealer busts slightly more often.
- 8,8 vs dealer Ace: S17 says split. H17 says split (same). Unchanged but listed because some old charts conflate it.
- Hard 15 vs dealer Ace (with surrender): S17 hit. H17 surrender if allowed.
- Hard 17 vs dealer Ace (with surrender): S17 stand. H17 surrender if allowed.
- A,8 (soft 19) vs dealer Ace: S17 stand. H17 hit (rare but in the chart).
- Hard 11 vs Ace: same as above — most-cited H17 cell.
The biggest gap of those is the surrender cells. If the table offers late surrender AND hits soft 17, you should surrender hard 15 and hard 17 against a dealer Ace — both losing hands so often against an H17 dealer that giving up half your bet beats playing it out.
How to spot the rule in two seconds
Every blackjack table prints its house rules in the corner of the layout. Usually it's directly under the 'Blackjack pays 3 to 2' (or '6 to 5') line, in smaller type. The two phrases to scan for:
- 'Dealer must hit soft 17' or 'Dealer hits on all 17s' = H17
- 'Dealer must stand on all 17s' or 'Dealer stands on soft 17' = S17
If the layout doesn't mention soft 17 at all, the table is almost certainly H17 — the casino doesn't print rules it can leverage against you. S17 is the player-favorable rule and properties advertising it usually call it out.
The cross-product with deck count
One trap: a 1D or 2D game often comes paired with H17 specifically to give back the deck-count edge. A naive comparison says single deck is better than six deck (-0.48% off baseline), but if the 1D table is also H17 (+0.22%) and only pays 6:5 (+1.39%), the actual edge is much worse than a clean 6D-S17 table. Let's run the math:
- 6D S17 DAS no-LS 3:2: 0.50% baseline
- 1D H17 DAS no-LS 6:5: 0.50% - 0.48% + 0.22% + 1.39% = 1.63%
The 'single deck' game costs you 3x more per hand than the 6-deck game next to it. This is the most-missed nuance on the casino floor for players who learned that fewer decks is better.
How to play H17 if you're stuck with it
If you're at an H17 table because every table in the house is H17 (common in Strip casinos, near-universal in 6:5-payout shops), here's the adjustment list:
- Use an H17 basic strategy chart, not the S17 chart you might have memorized first.
- Double 11 vs dealer Ace.
- Surrender hard 15 and hard 17 vs dealer Ace if LS is allowed.
- Double soft 18 and soft 19 vs dealer 6.
- Otherwise the chart is identical to S17 — just remember those four cells.
If you're a counter, the index plays also shift slightly. The Illustrious 18 indices for hard 16 vs T, hard 15 vs T, and insurance are unaffected. The soft-18 vs 9 and soft-18 vs A indices tighten by half a unit under H17. Most working counters carry both charts and switch based on the table.
Which rule to walk past, which to play
Order of priority when scouting a blackjack table, by EV impact:
- BJ payout: 3:2 is mandatory. 6:5 is a hard walk-away.
- Soft 17 rule: S17 preferred. H17 is acceptable if other rules are good.
- Deck count: 6D or 8D acceptable. 1D or 2D only if BJ pays 3:2 AND S17.
- DAS: required. No-DAS games add 0.14% and aren't worth your bankroll.
- Surrender: bonus, not required. Saves 0.07% when present.
An S17 game with 3:2 BJ and DAS is the standard 'beatable' shape. H17 with everything else clean is still playable. H17 paired with 6:5 is the modern Strip trap — walk past it.