The Doubling Cube in Backgammon: Rules, Strategy, and When to Double

Published on July 8, 2026

The doubling cube is one of the elements that sets backgammon apart from most other classic board games: it lets you raise the stakes of a game in progress — turning the decision of when to double, take, or pass into its own strategic layer on top of the moves on the board.

What is the doubling cube?

Unlike the two regular dice, the doubling cube doesn’t show numbers 1 through 6, but the values 2, 4, 8, 16, 32, and 64. At the start of a game it sits in the middle of the board with the 64 face up — a signal that no one has doubled yet and both players hold equal rights to it.

The basic rules of doubling

Only the player on roll may double, and only before rolling their own dice.
The opponent then has two options: take (the stakes are now doubled and play continues) or pass (the game ends immediately, at the previous, not-yet-doubled stake).
If the opponent takes, they own the doubling cube exclusively afterward — only they may double again later (a so-called redouble), not the original doubler.
This principle repeats: the cube moves to the other player every time it’s taken.

Why double at all?

A player who’s clearly ahead in a game has an interest in raising the stakes while their advantage still holds. At the same time, the double forces the opponent into a decision: if they take, they keep playing at a disadvantage for a higher stake. If they pass, they lose for certain, but only the smaller, original amount. This exact trade-off makes the doubling cube its own tactical tool — just as with priming or a deliberate backgame, a well-timed double can be the difference between winning and losing a game.

When should you double? The percentage rule of thumb

For pure race situations with no contact possible between the checkers, a simple rule of thumb has become established: if you’re leading by roughly 10% of your own pip count, you should double. The opponent’s deficit can be up to roughly 12-13% and still be a correct take — only beyond that does passing become correct.

Important: the required percentages get larger the shorter the race is. A lead of 88 to 80 pips (10%) is a correct double, but a lead of 44 to 40 pips (also 10%) is no longer necessarily one — with fewer pips left on the board, the lead tends to need to be a larger percentage for the rule to still hold reliably.

This rule of thumb comes from Peter Youngerman’s article Doubling Cube Strategy on the reference site Backgammon Galore.

What about positions with contact?

As soon as hitting is still possible — so with blockades, open blots, or an ongoing holding game — the pure pip count is no longer enough to make a reliable doubling decision. Additional factors come into play here: how many checkers are still at risk, how stable is your own structure, what rollout probabilities does the concrete position produce. For these situations, programs like GNU Backgammon or XG provide an exact evaluation through rollouts that a simple percentage rule can’t deliver.

The Jacoby rule and the doubling cube

In money games — that is, when playing for stakes — the Jacoby rule often comes into play as well: it states that gammons and backgammons only count if the doubling cube has already been used beforehand. This prevents players from deliberately avoiding an early double just to gamble on a gammon.

Caution at very high values

One essential tip for handling the doubling cube: only double when you’re genuinely confident in your better position — because as soon as the opponent takes, the cube belongs to them, and they can redouble themselves if the game turns around. Experienced players therefore generally don’t double beyond 4 to 8 times the original stake, even though the cube theoretically goes up to 64.

A common mistake: doubling too late or too early

Two opposite mistakes come up especially often with the doubling cube: doubling too late gives away value, because the opponent would now correctly pass a double they should actually have had to take earlier. Doubling too early — for instance with a lead that’s still too narrow — voluntarily hands the opponent the cube and, with it, control over future doubles, without having received a sufficient advantage in return. For more on the timing of different playing styles, read our strategy guide.

About the Author

Ulf Mayer

I love backgammon in all its forms – whether it's a quick match on my smartphone to pass the time, or a glass of wine alongside a beautiful wooden board with family and friends. As the founder of backgammon-meister.de, I share my passion, tactics, and tips to help both beginners and ambitious players dominate their next match. Dice cup ready? Let's master the game!

backgammon-meister.de has been online since 2008.