When to split in blackjack?

Blackjack is a game where every option can tip the balance between wins and losses. Imagine: you receive two identical cards, you have the option to split your hand to form two… but when should you do it? 

The rules of splitting in blackjack

When a player receives two cards of the same value, they have the option to split the hand into two separate hands. Each new hand receives a second card and is then played normally.

To create the second hand, the player must place a new bet, identical to the initial bet.

Specific rules depending on the casino

These rules can influence the advantage created by splitting:

• In most casinos, if you split aces, you only receive one additional card per ace, and it is often forbidden to split them again.
• Some rules allow you to split again if a third identical card is dealt after a split (for example, you split two 8s and then receive another 8).
• Some casinos allow doubling down after splitting (for example, if you split two 6s and receive a 5, you can double down on 11). Others prohibit this option.
• If you split aces and get an ace + a 10, this is not usually considered a natural blackjack, but simply a 21.
• In games known as ‘no-hole-card’ games, the dealer does not reveal their second card until the player has played, making splitting against an ace or 10 even riskier.

Be sure to check the specific rules of the blackjack game you are playing in order to make the best possible choice.

Tips on splitting in blackjack

A golden rule: always split aces and 8s

Right from the start of the basic strategy, a mantra is stated: ‘always split aces and 8s.’ This simple rule hides a powerful logic. 

A 16 (8+8) is considered the worst hand in blackjack; trying to hit on a 16 carries a risk of busting of over 60%. By splitting your 8s, you turn this problematic hand into two stronger opportunities, with a high probability of hitting 18 or better.

A pair of aces is worth either 2 or a soft 12, two weak hands, but splitting them gives you two chances to reach 21, greatly increasing your chances of winning. This is so advantageous that most casinos impose limits, such as only giving one card per split ace or refusing natural blackjacks on these hands.

When the dealer has a 4, 5 or 6… take advantage of the weakness

A subtle but decisive strategy is based on observing the dealer’s face-up card. If the dealer shows a 4, 5 or 6, their chances of busting are particularly high (up to 42%). This increased risk allows the player to capitalise: even with modest hands, splitting can be a good idea, as the dealer has a good chance of busting, regardless of the player’s draws.

Other pairs to split depending on the situation

The analysis becomes more nuanced when dealing with other pairs.

• 2s, 3s, 7s: split if the dealer shows a 7 or less. These hands become stronger individually than when combined, but only if the dealer does not have a high card.
• 6s: split if the dealer shows a card between 2 and 6. Otherwise, it is better to keep these cards together.
• 9s: this pair is usually split if the dealer shows 2 to 6, 8 or 9, but avoid splitting against a 7 (in this case, you already have a very decent hand of 18).

When not to split… or play it safe

Not all pairs are worth splitting.

• 5s: it is better to double down if the dealer has between 2 and 9, or wait if this is not allowed. Splitting 5s means you lose the opportunity to maximise a strong hand of 10.
• 4s: if the rules do not allow you to double down after a split, only split against 2-4; otherwise, it is better to hit.
• Against the dealer’s ace: unless you have a pair of aces, avoid splitting — the dealer often has a high probability of getting a strong hand, up to 87% according to statistics.
• 10s (and face cards): with an already strong hand (20), splitting is disadvantageous, except in very advanced cases (card counting), and even then, it can attract the casino’s attention.

A strategy to be adopted with discernment

While it may be tempting to rely on instinct, blackjack rewards those who follow strategy, not those who improvise. Here is the roadmap:

• Always split aces and 8s.
• Analyse the dealer’s card: a 4-6 is often a good time to split.
• Moderate according to the type of pair and the dealer’s hand: 2s, 3s, 6s, 7s, 9s may be worth splitting in some cases.
• Do not split 5s and 10s, or against the dealer’s ace, except in very specific cases.
• Adapt to the table rules: no hole card, no doubling after splitting, and whether or not you can resplit all play a part in the equation.