When to Split in Blackjack

The Golden Rules of Splitting

Two rules apply in almost every blackjack game, regardless of the number of decks or dealer rules:

Always split Aces. Two Aces as a pair gives you a soft 12 — a terrible hand. Split them and each Ace becomes the start of a potentially strong new hand. Most casinos only allow one additional card per split Ace, but it's still the correct play every time.

Always split 8s. A pair of 8s equals 16 — the single worst hand in blackjack. You lose more often than not if you stand, and hitting risks busting. Split the 8s and you start two fresh hands from 8, which is a neutral starting point you can build on.

The Never-Split Rules

Just as important as knowing when to split is knowing when not to:

Never split 10s. A pair of 10s is a 20 — one of the strongest hands possible. You will win this hand the vast majority of the time. Splitting it turns a near-certain win into two uncertain ones. Players who split 10s are throwing away expected value.

Never split 5s. A pair of 5s equals 10 — an excellent hand to double down on. Splitting turns one strong hand into two weak hands starting from 5. Always treat 5-5 as a 10 and double down instead.

Complete Pair Splitting Chart

For every other pair, the correct decision depends on the dealer's up-card:

The Tricky Pairs: 9s, 7s, 6s, 4s

9-9 (soft 18): Split against dealer 2–6 and 8–9. Stand against dealer 7 (you have 18 and the dealer likely has 17), 10, and Ace.

7-7: Split against dealer 2–7 only. Against dealer 8 or higher, the dealer is likely to have a strong hand — hit instead.

6-6: Split against dealer 2–6 only. Dealer 7 and above means you're likely behind; just hit.

4-4: Only split against dealer 5 or 6 (their weakest cards). In all other situations, treat 4-4 as an 8 and hit.

Re-splitting and Split Aces Rules

Most casinos allow re-splitting — if you split a pair and receive another matching card, you can split again, up to 3 or 4 hands total. Always take this option when basic strategy says to split.

Split Aces restriction: Almost all casinos only deal one card to each split Ace and do not allow re-splitting Aces. A 10-value card on a split Ace counts as 21, not blackjack — so it pays even money, not 3:2. Despite this restriction, splitting Aces is always correct.

Double after split (DAS): Some games allow you to double down after splitting. When DAS is available, you can split 2s, 3s, and 4s more aggressively, even against dealer 7 in some cases.

For live dealer-specific rule variations and how they affect splitting decisions, see Live Casino Guides' live blackjack splitting strategy guide.