The Doubling Cube in Backgammon

What the doubling cube is

The doubling cube looks like a big die, but its faces show 2, 4, 8, 16, 32 and 64. It isn't rolled. It records how much the current game is worth. At the start the cube sits in the middle, usually with 64 facing up, which by convention means the game is worth 1. It was added to backgammon in the 1920s in New York clubs, and it changed the game more than anything since: today most club and tournament play uses it.

How doubling works

1. Offer. At the start of your turn, before rolling, you may offer a double: "I think I'm winning — let's play for twice as much."
2. Take or drop. Your opponent either takes — the game is now worth 2 and they place the cube on their side — or drops (passes), conceding the game at its current value of 1.
3. Redouble. Only the player who owns the cube may double next. If they redouble to 4 and you take, you own the cube again.
4. End of game. The cube value multiplies the result: a gammon with the cube on 4 is worth 8 points.

The point of the cube is that you don't have to play out hopeless games. If your position is bad enough, dropping costs you less than losing a doubled game — possibly a doubled gammon.

When to double, when to take

The basic rule of thumb is about winning chances. Taking a double makes sense if you still win at least about 25% of the time (ignoring gammons): over four such games you lose 2 points three times and win 2 once, a net loss of 4 — exactly what you'd lose by dropping all four. Below 25%, drop; above it, take. Gammon chances, owning the cube and the match score all shift that line, which is why cube decisions are the deepest part of modern backgammon.

The Crawford rule

In match play, a player who is behind would always double — they have nothing to lose. To stop that, the Crawford rule says: when one player first reaches one point away from winning the match, the next game is played without the cube. That one game is the Crawford game. After it, the cube is back in play. Almost every tournament uses it.

The Jacoby rule and other house rules

• Jacoby rule — used outside match play: gammons and backgammons count only as single games unless the cube has been turned at least once.
• Beavers — a player who is doubled may immediately redouble while keeping the cube; it's a casual-play option, not a tournament rule.
• Automatic doubles — some groups double the starting value when the opening roll is a tie. Agree on this before you play.
• Chouette — a format for three or more people: one player "in the box" plays a team led by a captain, and each team member may have their own cube.

Backgammon without the doubling cube

The cube is a separate layer on top of backgammon, and plenty of people play without it — in most of Turkey, Greece, the Caucasus and Central Asia, the cube was never part of the game. Without it a game is worth:

That's how NARDEON plays. Matches go to 1, 3, 5 or 7 points, there's no cube, and because there's no cube there's no Crawford game either. In long nardy there's no backgammon (koks): a win is 1 or 2. More about scoring: gammon and backgammon.

Without a cube, gammons matter even more: since you can't settle a lost game early, saving the gammon is often what decides the match. The backgammon strategy page covers when to play for a gammon and when to settle for a single game.

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Updated: October 24, 2026