Backgammon dice
Backgammon uses two ordinary dice each turn, plus one special die that is never rolled. Here is the equipment, the rules for rolling and for doubles, what the doubling die does, and what the odds look like.
What is in a set
- Four dice: two ordinary six-sided dice for each player, usually in each player's colour.
- Two dice cups, one each.
- One doubling cube: a larger die marked 2, 4, 8, 16, 32 and 64.
You only ever roll two dice at a time. Having your own pair and cup is a convention that keeps the game tidy and stops arguments about whose turn it is: a turn ends when you pick up your dice.
How to roll
Put both dice in the cup, shake, and roll them out onto the board to your right, the half of the board between the bar and your right-hand edge. Both dice must land flat in that half. If either die lands on the other half, off the board, on a checker or tilted against something (a "cocked" die), both dice are rolled again.
The game begins with each player rolling a single die. The higher number moves first, using both numbers rolled; ties are rolled again. From then on, players take turns rolling two dice. See how to play for the full rules.
Rolling doubles
When both dice show the same number you play that number four times. A roll of 5-5 is four moves of 5, twenty pips in all; 6-6 is twenty-four. You can move one checker four times, four checkers once each, or any mix, as long as each move is legal. You must use as many of the four moves as you can.
One in six rolls is a double, and doubles are why the average roll is worth about 8.17 pips rather than 7. Doubles do not count on the opening roll, because each player rolls one die and a tie is simply rolled again.
The doubling die
The big die is the doubling cube. It is never rolled. At the start it sits in the middle on 64, meaning the game is worth 1. Before rolling, a player who thinks they are ahead may turn it to 2 and offer it to their opponent, who must either take (the game is now worth 2 and they own the cube) or drop (concede one point). The doubling cube guide explains when to double and take, and the Crawford rule covers the one game in a match where it is not used.
Dice odds at a glance
Two dice give 36 equally likely outcomes. A few numbers worth knowing (every one is worked out on the odds and probabilities page):
| Event | Rolls out of 36 | Chance |
|---|---|---|
| Any double | 6 | 16.7% |
| A specific double, such as 6-6 | 1 | 2.8% |
| A specific non-double, such as 6-5 | 2 | 5.6% |
| At least one 6 (or any given number) | 11 | 30.6% |
| Hitting a blot 6 pips away | 17 | 47.2% |
| Hitting a blot 7 pips away | 6 | 16.7% |
Precision dice and dice cups
Cheap dice with drilled pips and rounded corners can be very slightly unbalanced. Tournament players prefer precision dice: sharp-edged, transparent cubes machined to tight tolerances, with filled pips so each face weighs the same. Many tournaments supply precision dice and require them for important matches.
Dice cups are usually leather or felt-lined. Tournament cups have a lip or ridge inside so dice cannot slide out without tumbling. Some events also use a dice tower or tray to rule out any controlled roll.
Online dice
In online play a random number generator chooses each roll. A good generator gives all 36 outcomes the same chance on every turn, independent of the last roll and of the position. Players often feel online dice are streaky: people remember the double 6 that beat them and forget the many ordinary rolls. Over many games the counts match the odds above. For the streak odds and a do-it-yourself test, see is online backgammon rigged?
In Backgammon Lounge, games against the computer use your device's secure random number generator, and games against a friend online are rolled by the server, so neither player can influence the dice. The daily challenge is the one exception: everyone gets the same seeded dice that day, so scores can be compared. Roll the dice now.
Questions
How many dice do you use in backgammon?
Each turn you roll two ordinary six-sided dice. A full set has four, a pair for each player with their own cup, plus the doubling cube, which has numbers on it but is never rolled.
What is the doubling die in backgammon?
The large die marked 2, 4, 8, 16, 32 and 64 is the doubling cube. It is not rolled: it records the stakes of the game, and a player turns it to offer a double.
What happens when you roll doubles in backgammon?
You play the number four times instead of twice. 3-3 gives four moves of 3, which you can split between checkers however you like.
What if a die lands on the bar or off the board?
Under standard rules both dice must come to rest flat on the board to your right. If either die lands on the left side, on a checker, off the board or tilted ("cocked"), both are rolled again.
Are online backgammon dice fair?
Reputable sites use random number generators that give each of the 36 rolls the same chance. Online dice can feel streaky because people notice runs of luck, but over many games the counts match the odds.
Why do backgammon players use a dice cup?
Shaking the dice in a cup and rolling them out makes the result random and hard to control. Serious players use cups with a lip inside to stop dice sliding out unrolled.
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