The Backgammon Doubling Cube Explained

The cube has faces 2, 4, 8, 16, 32 and 64. Centered at the beginning, its 64 face normally represents the initial value of 1, not a 64-point game. It is not a die to roll and does not give extra checker moves.

With a centered cube, either player can make the first legal offer on their own turn before rolling. You cannot see your roll and then decide to double. The opponent answers before you roll and continue checker play.

The taker owns the cube. Only that player may propose the next double, on a later eligible turn before rolling. The original doubler cannot raise it again merely because the position improved. If the owner redoubles and the opponent takes, ownership switches again.

Cube decisions are strategic, not automatic consequences of a pip lead. Gammons, contact, future redoubles and the match score matter. A universal “take above 25%” rule is not a backgammon rule and would be misleading in match play.

An ordinary match ends when a player reaches or exceeds the agreed target. Each game begins again at value 1. In standard match play, played-out gammons and backgammons count even if nobody turned the cube.

When either player first becomes exactly one point short of the target, the next game is the Crawford game. Neither player may double in that one game. If the match continues afterward, cube use returns: this is post-Crawford play, not another Crawford game.

Current USBGF tournament rules also prohibit a player’s cube action when a win at the current value already wins their match. Cube ownership, pre-roll timing and event rules still apply after Crawford; “the cube is back” does not mean every player may offer it at every moment.

Separate optional money-play conventions: Jacoby, beavers and automatic doubles are not standard match rules. Jacoby changes the counting of unturned-cube gammons; beavers change immediate redouble/ownership handling. Do not silently apply them to the match-point examples above. Consult the tournament procedures and the event’s published rules.

These examples teach match points. Bet On Gammon’s online fantasy and prediction products do not offer money wagering. The cube’s game value is distinct from FC draft values and virtual Baxies.

• Reading a centered 64 face as an initial game value of 64.
• Doubling after seeing the roll, or redoubling when the opponent owns the cube.
• Charging the proposed cube value on a pass, or multiplying a pass into a gammon.
• Repeating Crawford every game at match point or treating money-play conventions as universal match rules.

Can I double with a checker on the bar?

Yes, if you otherwise have a legal cube action: correct ownership, your turn before rolling, no Crawford restriction, and no match-score prohibition. A closed board blocking entry does not by itself prevent doubling.

Who owns a centered cube?

Neither player exclusively owns it. Either may make the initial legal offer. After a take, the taker owns the cube and has the next redoubling right.

Is 25% always enough to take?

No. Simplified take-point arithmetic is not a universal rule. Match score, gammons, backgammons and future cube opportunities change the decision.

Original Bet On Gammon explanations, worked examples and illustrations. Further reading and rule references are listed below.

• USBGF — Beginner’s Guide to Backgammon ↗ — standard setup, checker play, bearing off, cube and results.
• USBGF — Tournament Rules ↗ — the governing rules hub.
• USBGF — Rules for In-Person Play ↗ — match and cube procedures; follow your event’s rules and director.

Beginner’s Guide to Backgammon brings the full game together. Use the rules reference for a compact check, or return to the learning order.