Understanding the Soft 17 Rule in Casino Blackjack
Published on November 12, 2018
The “soft 17 rule” in casino blackjack is the guideline a specific table at a specific casino has for how the dealer plays a hand with a total of soft 17.
This is an important enough rule that it warrants its own blog post. Don’t worry, though — it’s not such a complicated rule that it needs 3000 words of comprehensive coverage.
My guide to the soft 17 rule in casino blackjack is succinct, detailed, and accurate. Once you’ve read this post, you’ll understand this aspect of the game as well as most blackjack experts — including card counters.
I like to assume that anyone reading one of my posts is starting at zero. I’m not doing exactly that here, because I’m not explaining in detail all the rules of casino blackjack.
But I do want to draw the distinction between hard hands and soft hands.
Blackjack is a simple comparing game where the player and dealer each start with a two-card hand. The one with the higher total points for their hand wins the bet, but only if they keep their total to 21 or below. A total of 22 or higher is an automatic loss.
The cards have points based on their rank. The numbered cards have the same number of points as their numbers: 2, 3, 4, 5, 6, 7, 8, 9, and 10. The face cards (jack, queen, and king) are also worth 10 points each.
The only exception is the ace. No one would blame you for thinking that an ace is worth 1 point. It is, in fact, in many situations, worth a single point.
But it’s also worth 11 points.
When you have a hand with no aces in it, you have a hard total. This means that the total is what the total is.
For example, if you have a jack and a 3, you have a hard total of 13. There’s no wiggle room there. That’s the total.
But if you have an ace and a 3, you have a soft total. That’s because the ace counts as 11, but if you get a card that would otherwise give you a total of 22, you can count it as a 1 instead.
With an ace and a 3, you have a soft 14. If you hit that hand and get a 10, you have a hard 14. (Any hand where the ace must be considered 1 point to avoid busting is also considered a hard hand.)
The strategy for a player with a soft hand as opposed to a hard hand is significantly different. Since you have that added layer of protection from busting, the right move is often to play a soft total more aggressively.
But when we talk about a soft 17 “rule” in blackjack, we’re talking about how the dealer plays his hand.
When you’re playing a blackjack hand, you get to decide whether to stand, hit, split, or double down.
It doesn’t matter what the dealer thinks. It doesn’t matter if your decision doesn’t make sense logically or mathematically. You get to do what you want to.
The dealer, on the other hand, doesn’t get to make decisions or judgment calls about how to play her hand.
One of the most important rules for blackjack has to do with how a dealer’s total of 17 is handled.
The rule of thumb in most games of casino blackjack is that the dealer always hits a total of 16 or less and always stands on a total of 17 or more. This is the best possible situation for the player as it relates to the soft 17 rule.
And this rule doesn’t take into account whether the total is soft or hard.
But in some casinos, at some blackjack tables, the dealer is required to hit a soft total of 17. (Remember, a soft total of 17 is a hand which includes an ace. And that ace can be counted as 1 or 11, depending on which is more favorable.)
This actually improves the conditions of the game for the casino, but it hurts the game conditions for the player. It gives the dealer a slightly higher mathematical edge over the player.
It also has an effect on the correct strategy for playing each hand.
I cover both those subjects in the next two sections.
When you’re playing blackjack, there’s only one way to play each hand that has the highest expected value mathematically. When you put together a table with all the possible situations and the correct way to play those hands, you’ve put together a “basic strategy” table.
When gambling writers discuss how low the house edge is in blackjack, they’re assuming that you’re playing with perfect basic strategy.
You’ll see often see casinos with blackjack games where the house edge should only be 0.56% based on the rules in place, but the actual casino hold for the games is 4% or 5%.
This is because lots of players AREN’T using perfect strategy, and are actually making mistakes.
Basic strategy changes based on the conditions and rules of the blackjack game in which you’re playing, though.
In a game where the dealer hits on a soft 17, the correct basic strategy changes, but not by too much.
The big changes have to do with some of the doubling down strategies.
If the dealer hits soft 17, you should double down on an 11 if the dealer is showing an ace. You should also double down if you have a soft 19 and the dealer has a 6. Finally, you’ll double down on a soft 18 if the dealer has a 2.
The number of decks in play also matters. In a single-deck game, you’ll also hit a soft 18 if the dealer has an ace. In a game with four decks or more, you’ll also double down on a soft 17 versus a dealer 2.
The house edge is an approximation of the percentage of each of your bets that the casino will win from you in the long run. When I talk about the long run, I’m talking about thousands of hands. In the short run, especially the very short run, anything can happen.
So if I say that a game has a house edge of 0.56%, this means that the house is mathematically expected to win 56 cents on average every time I place a $100 bet.
You can use this to estimate how much money it will cost you per hour to play certain casino games. It’s just a matter of number of bets per hour, average bet size, and the house edge, all multiplied together.
If you’re playing in a game where your average bet size is $20, the hands per hour are 70, and the house edge is 0.56%, your expected hourly loss is as follows.
Changes to the rules conditions, especially when it relates to the dealer hitting a soft 17, affect the house edge. When a dealer hits a soft 17 instead of standing on it, the house edge goes up 0.2%.
That doesn’t seem like much, but the difference between 0.56% and 0.76% in the above example is the difference between $7.84/hour and $10.64/hour. That’s 1.5 times as much in average hourly losses.
Think of it as being like the difference between buying a movie ticket for $7.84 as opposed to buying a movie ticket for $10.64.
Some blackjack players think that this rule helps the player, not the dealer, because the dealer will bust more often.
It is true that the dealer will bust more often, but the dealer’s hand improves often enough that it more than compensates for this.
, here are the probabilities for the dealer’s final hand after hitting a soft 17 versus standing on a soft 17. (This assumes a 6-deck game.)
If the dealer stands on a soft 17, he has a 14.62% probability of a total of 18, a 14.04% probability of a total of 19, an 18.85% probability of a total of 20, and a 7.65% probability of a total of 21. He’ll bust 29.60% of the time.
But if the dealer hits that soft 17, he has a 14.82% probability of a total of 18, a 14.24% probability of a total of 19, a 19.06% probability of a total of 20, and a 7.86% probability of a total of 21. He’ll bust 30% of the time.
The probability of busting goes up by 0.4%, yes.
But the probability that the dealer will improve to one of these other hands increase by 0.8%, which is twice as big a gain on the winning side of things for the casino.
The soft 17 rule in casino blackjack is something every skilled blackjack player should be aware of and understand.
Blackjack is a simple game, but this one simple change has a surprisingly large effect on the house edge — raising it by 0.2%.
In games with this rule in effect, basic strategy changes, too. Most of these changes are minor, but serious blackjack players milk every 1/100 of 1% out of the game.