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Betfair zero-margin blackjack

• Rules and house edge
• Five-card 21 pays 2:1
• Basic strategy
• Four-card exceptions and unusual plays
• Recommended casinos
• Game location
• Credits

Betfair Zero margin blackjack

Betfair sports exchange and casino have a "Zero Lounge" games suite whose games all boast a full one hundred percent return. This is a unique - and welcome - online gambling concept.

The software is provided by Chartwell, and is browser-based. However, Betfair also has a Playtech download casino, which plays much faster.

Rules and house edge

The rules for the blackjack game are quite unusual. There are four standard rules...

• 8 deck
• S17
• D8

...and three unusual rules:

• Aces cannot be split
• Suited blackjack pays 2:1
• Five-card 21 pays 2:1

The more usual rules - 8D, S17, D8 and DAS - give a house edge of 0.59%.

Not being able to split aces is bad for the player, costing a further 0.17%, giving a grand total of 0.76%. Suited blackjack adds 0.56% and the five-card 21 adds 0.2%, giving an overall return of 100%.

Five-card 21 pays 2:1

This is an extremely unusual rule and I cannot recall any other instance of it in an online casino. Five-card 21 occurs relatively infrequently, but adds 0.2% to the player return:

Betfair five-card 21

On this occasion, I had a four-card hard 12 against dealer six, which would normally be a stand. In this game, the correct play is to hit, because of the guaranteed 2:1 payoff if you catch a nine - which I did:

Basic strategy

As alluded to above, the precise basic strategy for this game is dependent on the number of cards the hand contains - the automatic 2:1 payoff on a five-card 21 necessitates a handful of changes to four-card strategy. Other than that, the basic strategy is that of the standard eight deck DAS game. Additionally, the four-card exceptions are so rare that you could ignore them without sacrificing much.

H = hit
S = stand
D = double
P = split
H4 = Hit with four cards, otherwise stand.

Hard Totals
Betfair hard totals

Soft totals
Betfair soft totals

Betfair pairs
(Charts reproduced with the permission of Stanford Wong)

Four-card exceptions and unusual plays

To summarise the four-card exceptions:

• Hit 12 against 4, 5 and 6
• Hit 13 against 2, 3 and 4
• Hit 14 against 2
• Hit 17 against ace
• Hit soft 18 against 2, 3, 4, 5, 6 and 8

Note that the only exceptions occur with four cards. For hands containing three or five or more cards, there are no exceptions and the normal strategy should be followed.

Recommended casinos

This game is only found at Betfair.

There were a couple of bonus confiscation issues at Betfair a while back, which I commented on in my Betfair bonus confiscation issue blog article. The matter was not resolved to my complete satisfaction. However, I have seen no evidence of any other problems in the intervening period, and I have received and cashed out Betfair bonuses myself without any problem. I am confident you can play here safely, but be aware that if you take a bonus and play it using an auto-click robot programme, this is against the Betfair rules and they may remove the bonus upon cashout.

Game location

From the lobby of the download software, hover your mouse over "Zero Lounge", then click on "Zero Blackjack" in the sub-menu.

Betfair lobby screen

Alternatively, if you prefer to play the browser-based game, in the "card games" menu click the "12 more" tab. Zero blackjack is located at the bottom of the list.


I would like to thank blackjack author and guru Stanford Wong for his kind permission to reproduce the basic strategy charts pertaining to this game in his book "Basic Blackjack". This material is copyrighted and may not be reproduced elsewhere without the author's consent.

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