Doubling Cube Basics Rules

The doubling cube is the very heart of backgammon and makes it the exciting game that it is. Without it the game might well have died off in the 1920`s. Despite the fact that it has now been in existence for eighty years it is also the least well understood and most difficult part of the game.

Each game starts at a stake of 1 point. During the course of the game, a player who feels he (or she) has a sufficient advantage may propose doubling the stakes. The player does this by turning the doubling cube to the next appropriate value. Each face of the doubling cube bears a number to record progressive doubles and redoubles, starting with 2 and going on to 4, 8, 16, 32 and 64. At the commencement of play, the doubling cube rests to one side of the board, in the centre between the two players with a displayed value of 64 (there is no 1 on the doubling cube so 64 serves as 1 at the start of the game). At any point during the game, a player who thinks he is sufficiently ahead may propose doubling the stakes, in the first instance by turning the cube to 2, and so on.

A player may double any time it is his turn and he has not yet rolled the dice. A player who is offered a double may refuse, in which case he concedes the game and pays one point. Otherwise he must accept the double and play on for the new higher stake. A player who accepts a double becomes the owner of the cube , which is placed on his side of the board (showing the new value), and only he may make the next double.

Subsequent doubles in the same game are called ' redoubles '. If a player refuses a redouble he must pay the number of points that were at stake prior to the redouble. Otherwise he becomes the new owner of the cube and the game continues at twice the previous stake. There is no limit to the number of times a double may be offered in one game.

It may seem counter-intuitive to accept the doubling of the stakes when you stand worse in a game. However, consider the following two scenarios:

1. In four games Player A doubles Player B in each game. Player B drops all four doubles and is therefore down four points (-4).
2. In four games Player A doubles Player B in each game but this time Player B accepts the doubles. He goes on to lose three games but wins the fourth game. He loses two points in each of the games he loses (-6) and wins two points in the game he wins (+2). His net result is -4 points. The same as scenario 1.

This gives us the basic rule of doubling - if you can expect to win 25% of the time from any specific position then you can (and should) accept a double .

Doubling is far more complex than this because cube ownership, psychology, gammons and backgammons (and in tournaments the match score) all play a part in doubling decisions but that is beyond the scope of this first article on the topic. As we progress we will gradually add levels of complexity.

Note that the doubling cube is not used in backgammon variations played in the Middle East such as Turkish Tavla. Nevertheless, it can be used in any other games. For example, I have played chess and scrabble with a doubling cube and I once watched a game of golf in which the doubling cube was in use - a five-figure sum changed hands at the eighteenth!

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