Casino & Table Games

Worst cards to split in blackjack

Never split

5s and 10-value pairs (10s, Jacks, Queens, Kings)¹²

Reason

Splitting these pairs usually reduces expected value compared to keeping the hand together³⁴

Key points

• Basic strategy treats 5s and 10-value pairs as the worst split candidates because the starting totals (10 or 20) are strong enough to stand or double.²⁴
• Splitting 5s gives two weak hands of 5 each; keeping them as a 10 allows doubling against a dealer upcard of 2–9.²⁴
• A pair of 10s totals 20, which beats any dealer hand except 21; splitting risks turning a near-certain win into two weaker hands.²⁴

Where this term is used

• Blackjack

Not the same as

• Blackjack strategy card — a full decision chart for all hands, not just the judgment about which pairs are poorest to split

Related terms

Sources

1. Blackjack - Estrategia básica (manos específicas) wizardofodds.com Confirms that 5s and 10-value pairs are the worst split candidates.
2. استراتيجية البلاك جاك لأربع مجموعات أوراق - دليل اللعب الأمثل wizardofodds.com Provides the basic-strategy rule never to split 5s and 10s.
3. 二十一點- 賠率奇才 wizardofodds.com Explains that splitting these pairs reduces expected value.
4. Blackjack - Basic Strategy (General) wizardofodds.com Gives the basic-strategy recommendation to keep the hand together.

Sources are drawn from regulators, universities and published research, and each one is labelled with what it actually is — a preprint is not called a paper. Bookmaker and affiliate pages are never cited here, because a page that sells betting is not a neutral authority on it.