Blackjack Strategy: When to Double Down

Dean Ryan

August 26th, 2019

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Doubling down is one of the most thrilling moves in blackjack. It allows you to double your bet in the middle of a hand in exchange for one extra card. It’s a risky gamble, as it usually ends your betting - if you receive a particularly low second card you can’t hit again.

This can lead to more timid players avoiding the double bet, and more adventurous players making it far too often. It's important to try and strike a balance between sensible safe play, such as using a statistical strategy, and risky double downs in order to maximise your potential winnings.

When to Double Down

Fortunately, basic strategies for blackjack have been meticulously mapped using mathematical probability, designed to tell you exactly when is best (in the long run) to double down. There are three situations when it’s best to double down, explained below.

In all of these situations you can’t go bust and are in the most likely position to finish with a high hand, while statistics indicate that the dealer is in the most likely position to lose the hand.

Hard 9 Against the Dealer’s Low Cards

When you are dealt a total of 9, double down when the dealer shows a card between 2 and 6 (any card below 7, not including the Ace). This must be a hard 9; meaning there is no Ace in your hand – so the combinations could be 2-7, 3-6 or 4-5. If you have A-8 (a soft 9), it’s best to stand, regardless of what the dealer shows.

Soft 16 To 18 Against the Dealer’s Low Cards

If you have an Ace and either a 5, 6 or 7 giving you a ‘soft’ total of 16 to 18 and the dealer shows a card from 2 to 6, this is a great time to double your bet. With an Ace and a lower card (2 to 4) it is better to just hit, as you are less likely to end with a high hand.

Hard 10 Or 11 Against Any Lower Dealer Card

A hard 10 or 11 puts you in a powerful position – that is, with any two cards, not including an ace, that make 10 or 11 (2-8, 2-9, 3-7, 3-8, 4-6, 4-7, 5-6). If the dealer has a lower total, it's time to double down.

Pay Attention to the Rules

In almost every Blackjack game this strategy should stay true. However, be aware that the rules of Blackjack do vary between casinos, which can affect your decision making. If it’s possible to double with 3 or more cards, then you may find additional hands when you could double down, so pay attention to your total.

On the other hand, you might find situations where the rules say you can’t double when the strategy says you should – such as on soft hands (those with an Ace). If you can’t double down when you'd like, be sure to hit instead. To try this double down strategy out in a cash game before hitting a real-life casino, check out the best sites for playing online blackjack!

FAQs – Doubling Down in Blackjack 101

Doubling down in Blackjack allows the player an option to double their wager following receipt of their original two cards. You then get dealt one – and only one – additional card. Then it’s you versus the dealer to decide who wins.

A player doubles down because the situation looks positive so they risk more to hopefully win more. As you can control when to double down, this is a powerful tool for the player who can spot the perfect opportunity. Here are a few specific instances where it pays to know where you stand.

Can you Double Down after Hitting?

A player cannot hit and then choose to double down, the double down option occurs only after the initial two cards are dealt by the dealer and the player must then decide whether to go for the double down at that moment or not. The opportunity to double down is limited to this point in a hand.

Can you Split and Double Down?

It is important the player understands the optimal situations to split and double down. The player can split their cards if they are dealt a matching pair e.g. 5-5, 7-7, J-J.

The player must cover the second hand with the bet size of their first bet and the dealer deals a second card to complete both hands. A further double down is not usually permitted. Always check the casino rules whether playing live or online as there are often incentives hidden within the rules designed to encourage players to play.

Should you Always Double Down on 11?

As the player and dealer aim to get as close to 21 as possible in order to win the hand, the player is in a strong position when holding 11 after two cards are dealt. If the dealer is showing a lower card than a 10, it is good strategy to double down.

If the casino rules dictate the dealer must hit soft 17, you should always double down on 11 no matter what the dealers up card.