Splitting Tens in Blackjack: Keep Your Hard 20

No—under ordinary basic strategy, you should not split two tens: keep hard 20 and stand, including against a dealer 5 or 6. Splitting creates two hands and requires an additional bet for the second hand. Card-counting deviations are a separate case, not the ordinary recommendation. This distinction is supported by Nairn’s calculations and the published Wizard of Odds index numbers.

What to do against each dealer upcard

The current basic-strategy tool returns Stand for two tens against all ten dealer upcard values under its six-deck default setup. These are results from the project’s model, not a claim about every blackjack variation.

The default rules are six decks; dealer stands on soft 17; doubling after splitting and on any first two cards; late surrender; US dealer peek for blackjack; and a 3:2 blackjack payout. Soft 17 means a total of 17 with an ace counted as 11.

The implementation uses an infinite-shoe approximation, recalculates for rules and applies documented deck-count overrides. It does not enumerate every possible outcome from a finite set of remaining cards. Separately, the Wizard of Odds single-deck strategy chart says to treat two tens as hard 20 when there is no separate tens-splitting row. Hard 20 is a total of 20 without an ace counted as 11.

Why stand even against dealer 5 or 6?

Keeping a made 20 is better under ordinary basic strategy than breaking it into two unfinished hands. A weak dealer upcard may make two potential winning hands seem attractive, but the relevant comparison is the expected value of the actions—not the appeal of a possible outcome.

Expected value (EV) is the model’s average result per original bet under stated conditions. It is not a win probability or a prediction for an individual hand.

Nairn’s paper, page 15, provides an exact comparison for one deck, 10-10 against dealer 6, with the dealer standing on soft 17. The comparison is between standing with a maximum of one hand and splitting to a maximum of two hands. Values are expressed in units of the original bet.

For a hypothetical $25 original bet, that EV difference is $4.30745, rounded to the nearest cent as $4.31. This is an expected-value difference, not a guaranteed loss from a particular split. These figures apply only to the stated single-deck model; do not apply them to six-deck games or other rules.

A successful split does not disprove the comparison. The decision is evaluated before the next cards are dealt, not by the outcome of one completed hand.

Which cards count as tens, and can you split them?

A ten, jack, queen and king are each a 10-value card, but equal point values do not mean equal ranks. Whether you can split a king and queen, for example, depends on the table rules.

Some rules allow splitting cards of equal value; others require matching ranks. Do not assume that mixed-rank tens are eligible to split. For the basic-strategy decision, the important point is that two 10-value cards already make 20.

When can card counting change the decision?

Splitting tens can be a card-counting deviation when the remaining card composition changes the relative EV of the actions. The Wizard of Odds Hi-Lo Illustrious 18 table publishes these index examples:

The source lists a six-deck liberal Vegas game with the dealer standing on soft 17, late surrender, doubling after splitting and resplitting up to four hands. This is a different model from Nairn’s single-deck example above.

The Hi-Lo count is a card-counting system that assigns +1 to cards 2–6, 0 to cards 7–9, and −1 to 10-value cards and aces. The cumulative total is the running count. The true count is the running count normalized by the estimated number of decks remaining, as explained in the Wizard of Odds Hi-Lo guide.

An index number sets the threshold for an index play: a change from basic strategy within a particular counting system and rule set. The published +5 and +4 examples are not universal thresholds and should not be transferred to another game or true-count method. If you are not tracking the remaining card composition, these exceptions do not change the ordinary answer: keep 20 and stand.

How to check two tens in the strategy tool

Open the basic-strategy tool, choose two tens and a dealer 6, and the current interface returns Stand. That means taking no further card and keeping your 20.

1. Use the visible card-picker buttons to select T♠ and T♣ as your cards.
2. Select 6♥ as the dealer’s upcard.
3. Read Stand, the displayed recommended action.

English strategy lookup showing T♠ and T♣ for the player, dealer 6♥, and the recommended action Stand.

Local development interface showing two tens against dealer 6, captured at 390 CSS px with DPR 2. This is not a production-site or external-casino screenshot.

The tool provides a basic-strategy action under its current model and settings. It does not calculate exact split EV for a finite set of remaining cards, incorporate your true count or verify the rules of an outside game. For this ordinary two-tens decision, its answer is clear: keep hard 20 and stand.