The doubling cube

The cube turns every game into a bet you can raise. Here is how it works and how to decide when to double, take or drop.

How the cube works

The game starts with the cube in the middle at 1 (it shows 64, its highest face). At the start of your turn, before rolling, you may double. Your opponent then chooses:

• Take: the game continues worth twice as much, and your opponent now owns the cube. Only they may double next (a redouble to 4).
• Drop (or pass): they concede the game at its value before the double.

Gammons and backgammons multiply the cube: a gammon with the cube on 4 is worth 8 points.

When to take: the 25 percent rule

If you drop, you lose 1 point for sure. If you take, you play for 2. Ignoring gammons and later redoubles, taking costs less than dropping whenever you win at least 25 percent of the time. Owning the cube makes takes a little better still, because you can redouble if the game turns. Gammon chances against you make takes worse.

When to double

• Double when you are clearly ahead and your position could get much better soon: a blitz under way, a strong prime, or a racing lead of about 8 to 10 percent.
• Do not double when you are so far ahead that your opponent should drop and you have good gammon chances: play on for the gammon (too good to double).
• In a race, doubling with a lead of 8 percent or more and taking when behind by up to about 12 percent is a good rule of thumb.

The cube in match play

In a match, the score changes cube decisions: when trailing, take more freely and double earlier; when leading, be more careful. When a player first reaches one point from victory, the next game is the Crawford game and the cube may not be used. After it, the trailing player should double at the first chance, because they have nothing extra to lose.

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