The Soft 17 rule in blackjack is one of the most important rules, not only because it completely changes the way the dealer plays, but also because it affects the house advantage and your own playing strategy.

What is a soft 17 in blackjack?

Literally, soft 17 in Blackjack is another name for a hand worth 17 which contains an ace that counts as either 1 or 11. A soft hand cannot be overbought if you take one more card.

On the other hand, a hard hand is just a hand without an ace, or a hand with an ace that can be broken if you take one more card.

Soft 17 can be made in a number of ways. The Ace-6 hand is the most common Soft 17 hand known to most blackjack players, but you can also form Soft 17 with 3 or more cards seeing the Ace is counted as 11 or 1.

Examples of this are the Ace-3-3 and Ace-Ace-2-4 hands. Such Blackjack hands are called soft since you can't bust and you can still improve (or worsen!) your hand value by taking more cards.

For this reason, we play Soft 17 very differently from Hard 17 (where you would always stand). In a classic blackjack game of 8 decks, we hit or double Soft 17 depending on the dealer's face-up card and the type of rules that apply to us.

But Soft 17 is not just a type of blackjack hand. It is even more important because it is part of the second most important blackjack rule - the so-called Soft 17 rule. Read what is ace in Blackjack.

What is the Soft 17 Rule?

As a player, you can practically do whatever you want with your hand, but the dealer must abide by one simple rule. In a game of blackjack, the dealer either stands on a soft 17 or higher, or hits a soft 17, which means he can only stand on a hard 17 plus any 18 or higher.

After the number of decks used and the payout odds for blackjack itself, whether a dealer stands or hits on soft 17 is the second most important rule. You can tell which rule a game uses by the fact that it is always indicated on the table next to the blackjack odds.

In the United Kingdom, the S17 rule applies to all blackjack games, meaning the dealer draws to 16 and stops at 17 on all hands. The soft 17 rule is mainly found in America, but even there it is not applied at every table.

Unfortunately, the blackjack terms can be very confusing. You might think that S17 is the abbreviation for the Soft 17 rule, but it's not. S17 signify “Dealer Stands on Soft 17” and H17 signify “Dealer Hits on Soft 17”. So you know what I mean when I call the table H17 using the Soft 17 rule!

What difference does it make to the dealer?

If the dealer has to hit on a Soft 17 hand, this has two crucial effects on his chances. First, hitting soft 17 increases the probability that he will go broke. But it also increases the chance of getting a better hand.

These two aspects seem incompatible, but they are not. Either they outbid their hand, reach a similar sum to the one they already had, or they reach a better sum. The dealer's chances of getting overbought increase slightly by 0.4%, but their chances of reaching 18 or more increase by about 0.80%. So overall, the soft 17 rule is more favorable to the dealer's hand than to the player. Discover also what are the rules of blackjack.

How does the soft 17 rule affect the house advantage?

Of course, an S17 game is better for blackjack players and an H17 game is better for the house, but how big is the difference in blackjack play in the long run?

Assuming all other rules are the same, the difference between an H17 game and an S17 game for players in the long run is a whopping 0.2% in house advantage. To put this small number in outlook, typical European blackjack tables in online casinos have a house advantage of only 0.7%, so 0.2% is a significant amount.

You will receive $20 if you wager $10,000 on Blackjack in a year more in winnings at an S17 table than at an equivalent H17 table. In a game with razor-thin margins, every pound counts.

How do you adjust your strategy to the Soft 17 rule?

Let's take a look at the changes you need to make to basic strategies in blackjack in games with 4 or more decks, as this is the most commonly played format today.

In a blackjack game with multiple decks, there are 3 main situations where the optimal basic strategy decision depends on whether the dealer must hit or stand on soft 17. In all of these basic strategy scenarios, the hand is played more aggressively by doubling down.

If your table offers the surrender rule, there are 3 other situations where the strategy tables recommend that you adjust your basic blackjack strategy.

Blackjack games with only one deck are a dying breed, but if you are lucky enough to find one, the advice in the Soft 17 Basic Strategy Blackjack Charts changes again. This time there are only 2 adjustments to your basic strategy. The two appear when you have ensured variations of 18 when the dealer's upcard is an Ace. You should hit ace-7 against ace instead of standing, and you should split a pair of nines against ace when you would normally stand. Discover what are the strategies in Blackjack.

Card counting and the soft 17 rule?

If you are good at card counting, you will have a pretty good idea of how many high and low cards are left in the deck. This allows you to vary bet sizes and hand strategy to take advantage of favorable moments in your deck.

Card counting is an advanced blackjack skill and there are many variables to consider, not the least of which is what the dealer does with the soft 17. For example, if you have an 11 and the dealer's face up card is an Ace, you can double down depending on the True Count. In an S17 game the "True Count" must be plus 1 or higher, but in an H17 game it only needs to be -1 or higher.

There are several situations like this in the Illustrious 18 count strategy where the True Count required to deviate from the standard base strategy is lower in H17 games.