The doubling cube is basically an oversized 6-sided die with the numbers 2,4,8,16,32, and 64 on it. The doubling cube is used to keep track of the points at stake in a game of Backgammon. Before the game starts; the doubling cube is placed next to the board with the number 64 on top, indicating that the game is being played for one point. If one player feels he or she has the advantage during the game he or she may double the stakes of the game by turning the cube so that the number 2 is facing upward. Players may double only on their turn and before they roll the dice. The opponent may then choose to decline the double if he or she feels that the game is impossible to win. By declining, he or she forfeits the stakes of the game. He or she may also accept the double and play on for double the stakes. A player who accepts a double becomes the "owner of the cube" and only he or she may make the next double.

If a player refuses a re-double, he or she must pay the number of points that were at stake prior to the re-double. If the player accepts the re-double, he or she becomes the new "owner of the cube" and the game continues at twice the previous stakes. There is no limit to the number of times the stakes can be re-doubled.

Winning the game and keeping score

• The score according to the Doubling Cube
  Backgammon is won by the player who bears off all of his checkers first. If the losing player has borne off at least one checker, he loses only the value showing on the doubling cube.
• Gammon
  If the loser has not borne off any of his checkers, he or she is "gammoned". The winner now wins two times the value of the doubling cube.
• Backgammon
  If the loser has not borne off any of his checkers AND still has a checker on the bar or in the winner's home board, he is "backgammoned". The winner now wins three times the value of the doubling cube.

Please note that different backgammon sites might score the games differently. Therefore, always make sure that you know the rules before you start playing!