European no-hole-card rules (ENHC and OBO)

In most of Europe, Australia and much of Asia the dealer takes one card at the deal and draws the second only after every player has finished. With no hole card there is no blackjack check, so when you double or split against a ten or an ace you do so without knowing whether the dealer already holds a natural. What happens to those extra bets if the dealer then completes a blackjack is the settlement rule, and it decides both the house edge and how you should play.

How the deal differs

In a US peek game, the dealer showing an ace or ten-value card checks the hole card (after offering insurance on an ace) and ends the round immediately if it is a natural. Players lose only their original bets and never put a double or split bet at risk against a dealer blackjack.

In a no-hole-card game the dealer has a single face-up card throughout the players’ turns. Insurance is still offered against an ace in most jurisdictions. After the last player acts, the dealer draws the second card and, if that completes a natural, settles according to the house rule. The shoe game guide walks through both procedures.

The four settlement rules

The edge figures are Wizard of Odds’ rule-variation measurements. Wikipedia states the same principle in a sentence: OBO “has the same effect as a hole-card game.” The difference between the rules is entirely about exposure after the initial two cards, so the more you double and split the more the rule matters, and ENHC matters most. Wizard of Odds decomposes its 0.11 points into about 0.08 from doubling exposure and 0.03 from splitting exposure.

Ask at the table before assuming. “No hole card” is printed on the felt in many European casinos without any indication of which settlement applies; choosing a table gives the precise question to ask.

Why ENHC changes strategy

Basic strategy is built from expected values, and under ENHC the expected value of a double or split against a ten or ace includes the chance the dealer completes a natural and takes everything. Against an ace in a six-deck game that chance is roughly 31%; against a ten it is roughly 8%. A double that would be marginally profitable once a natural is ruled out becomes a clear loser when the extra unit is exposed to those outcomes.

Wizard of Odds’ Appendix 9 for six decks, S17, ENHC gives the figures per unit staked. Values are more negative than the peek-game equivalents because they are measured before the dealer’s natural has been excluded.

Three rules of thumb capture the changes, and Wizard of Odds lists the same three in its no-peek guidance:

1. Hit 11 against a 10 (and against an ace). The doubled unit is exposed to a natural and the gain from doubling is too small to cover it.
2. Hit a pair of 8s against a 10 or an ace. Splitting creates two bets, both lost to a natural. Under ENHC the pair plays as a hard 16: hit.
3. Hit a pair of aces against an ace. The same exposure argument. Against a ten, splitting aces remains correct because the split hands are strong enough to carry the risk.

Note the asymmetry: the strategy changes are confined to the ten and ace upcards. Against a 2 through 9 the dealer cannot have a natural, so every double and split is exactly as it would be in a peek game. If your table uses OBO settlement, there are no changes at all; use the ordinary multi-deck chart.

Other European rule differences

ENHC usually travels with other continental rules, and these matter separately. Wizard of Odds’ European chart assumes six decks, dealer stands on soft 17, doubling on hard 9 to 11 only, double after split allowed, no surrender, and full ENHC settlement, for a house edge of 0.62%. Compare that with 0.40% for the site’s six-deck S17 DAS profile: 0.11 points from ENHC, about 0.09 from the doubling restriction, and a small residual.

Doubling on 9–11 only removes every soft double from the chart (soft 13 through soft 18 against 5 and 6, for instance, revert to hit or stand). The doubling guide and double and split rule variations list those cells. Some European and UK games also restrict splitting of ten-value cards to matched ranks or forbid resplitting; before September 2007 UK rules did not allow splitting 4s, 5s or 10s, a restriction Wizard of Odds puts at only 0.003 points because basic strategy rarely splits those pairs anyway.

Surrender is uncommon in no-hole-card games, and where offered it is usually unavailable against an ace. Where early surrender against a ten is permitted, it is worth about 0.24 points to the player.

A worked comparison

Take a $20 bet on hard 11 against a dealer ten in a six-deck S17 game.

• Peek game: the dealer checks and has no natural. Under six-deck S17 rules doubling is worth +0.178 per unit against +0.119 for hitting (Wizard of Odds’ Appendix 9), so you double, risking $40 in total.
• ENHC: no check. Hitting is worth +0.032 per unit, or 64 cents on $20; doubling is worth +0.009 per unit, or 18 cents on $20, after accounting for the roughly 8% of the time the dealer turns over an ace and collects the full $40. Hit.

The difference between the two correct plays is only 46 cents on this hand, but a two-card 11 against a ten comes up on roughly one hand in 70 (about 4.75% of hands are a two-card 11 and about 31% of upcards are tens), the mistake of doubling it automatically repeats every time, and the same reflex on 8s and aces costs more. Study the specific hand pages such as hard 11 vs 10 and pair of 8s vs 10 with the peek-game profile in mind, then apply the three rules above when the felt says no hole card.

Related reading

• How rule variations change the house edge
• Double and split rule variations
• Blackjack rules around the world
• Pontoon and Australian blackjack