The temptation
A pair of tens (any two cards worth ten: a ten, jack, queen or king) is allowed to be split at most tables. It can look attractive: a ten is a strong start, so two hands each starting with a ten might seem better than one hand. In some situations, like the dealer showing a 5 or 6, the urge can feel stronger still.
Basic strategy says to stand every time. The reasoning is straightforward once you compare what you hold with what you would get.
What you hold
Two tens make a hard 20. Only a 21 beats it, and the dealer ends with 21 only a modest part of the time. Against a weak upcard, the dealer often busts or finishes below 20. Even against a strong upcard such as a 10 or ace, a 20 wins more often than it loses overall, although not by as much.
You are holding one of the strongest hands in the game before you have drawn another card. There is nothing to improve and nothing to risk. That is the baseline that splitting has to beat.
What you would get by splitting
Splitting means placing a second bet equal to the first and playing two hands. Each hand starts with a single ten and receives a new card.
- A ten as a starting hand is good, but a long way from a made 20. It needs another card to become anything.
- Some cards help: an ace gives 21 (although often paid as an ordinary win rather than a natural), a 9 gives 19, and a ten gives 20 again.
- Many cards do not: a 2 through 6 leaves a total of 12 to 16, which is a stiff hand that has to be played against the dealer’s card.
So each new hand has a good chance of landing somewhere worse than the 20 you started with. The sensible way to see this is that you are replacing a hand that is nearly certain to be strong with two hands that are only likely to be fairly strong.
The expected value comparison
Expected value is the average result per hand over a very large number of identical situations. The comparison has two sides.
Standing on 20. One bet at risk, with a high chance of winning it. Since the hand cannot improve, there are no draws that can ruin it.
Splitting. Two bets at risk. Each of the two hands is weaker than the 20 and has its own chance of ending badly.
A simple illustration, with deliberately round numbers that are not table figures: suppose you could count on the made 20 winning your single bet about three times out of four. If instead you split, each hand would need to be good enough that the average return on the added bet, and on the original bet which is now riding on a weaker hand, exceeded what the 20 gave you for free. Splitting gives up the sure strength of the first bet to gamble that the second will make up for it. The usual result is that the average comes out lower.
In other words, the second bet is not the problem on its own. The problem is that splitting lowers the quality of the first bet while adding the second. The extra bet does not make up for that trade.
What about against a weak dealer card?
This is where the myth is strongest. A dealer showing a 5 or 6 is the most likely to bust, so it feels natural to put more money out. But the 20 already benefits from that weakness: it wins when the dealer busts and also wins whenever the dealer stops below 20. Splitting spreads the bet over weaker hands, so you lose strength in exchange for a modest gain. The idea of getting more money on a vulnerable dealer is behind doubling and splitting weaker hands, as in the case for doubling on eleven, but a pair of tens does not need it.
Discussions of card counting sometimes mention splitting tens in rare situations when a count is extreme. That is a deviation based on information about the remaining cards, not a rule for regular play, and it does not apply to ordinary basic strategy. Casinos may also respond to counting, and rules vary.
Why the question comes up so often
- Aces and eights are always split, so players over-generalise to other pairs.
- Splitting feels active and ambitious, while standing feels passive.
- Fellow players may complain when you do or do not split. The suggestion that a particular choice affects the table is covered in the myth about the player at third base.
None of these is an argument about the numbers.
Keeping things in perspective
Standing on 20 is the correct play, but it does not make you a favourite over the long run. The house edge remains, and a 20 still loses to a dealer’s 21. Past hands do not make a future 20 more or less likely to win.
Treat the game as entertainment, only stake money you can afford to lose, and contact a local support service if gambling is causing you difficulty.