The dice are the engine of backgammon — every move begins with a roll. Yet despite their central role, many players don’t fully understand the rules around rolling, the probability of each outcome, or how to ensure fair dice. This guide covers everything you need to know: official rolling rules, probability tables, how doubles work, what the doubling cube is (and isn’t), and how to choose dice for serious play.
Key Takeaways
- Backgammon uses two standard six-sided dice per player, plus one doubling cube
- Dice must be rolled in your half of the board and must land flat — a cocked die is rerolled
- There are 36 possible dice combinations — 6 are doubles, 30 are non-doubles
- The most common sum is 7 (6 combinations); doubles occur on exactly 1-in-6 rolls
- Doubles give you four moves of that number — not two, making them twice as powerful
- The doubling cube is not a die — it tracks the game's current stake and has no random function
The Two Dice in Backgammon
Standard backgammon uses two six-sided dice per player. Each player has their own pair and rolls them in their own dice cup. The dice are numbered 1 through 6, with opposite faces summing to 7 (1 opposite 6, 2 opposite 5, 3 opposite 4).
A standard backgammon set includes:
- Two pairs of playing dice (one pair per player, typically in contrasting colours)
- Two dice cups (leather-lined or rigid)
- One doubling cube (numbered 2, 4, 8, 16, 32, 64 — this is NOT a playing die)
Dice Rolling Rules
Official Rules for Rolling
- Roll both dice simultaneously — one die alone is not a valid roll
- Roll in your half of the board — the inner table on your side (points 1–6 from your perspective)
- Dice must land flat — if a die leans against a checker, the board edge, or is askew, it is cocked and both dice must be rerolled
- Leave dice until move is complete — do not pick up the dice before moving your checkers. This prevents disputes about what was rolled.
- If you misread your dice — if you move based on a misread and your opponent points it out before the next roll, the move must be corrected
What Makes a Die “Cocked”?
A cocked die is any die that:
- Rests on a checker rather than lying flat on the board surface
- Leans against the wall or frame of the board
- Is tilted at an angle where it’s ambiguous which face is up
- Lands outside your half of the board (house rules vary on this)
When a cocked die occurs, both dice are rerolled — you don’t keep the other die’s result.
The First Roll (Opening Roll)
To determine who goes first, each player rolls one die. The player with the higher number moves first, using both dice (their own die and their opponent’s). If both roll the same number, reroll.
The opening roll cannot be a double (since both players roll one die each). The first player uses the two dice showing on the board and cannot double until their turn is established.
All 36 Dice Combinations
With two dice, there are exactly 36 possible combinations (6 × 6). Each is equally likely.
| Roll | Combinations | Count | Probability |
|---|---|---|---|
| 1-1 (double 1) | 1-1 | 1 | 2.78% |
| 2-1 | 2-1, 1-2 | 2 | 5.56% |
| 2-2 (double 2) | 2-2 | 1 | 2.78% |
| 3-1 | 3-1, 1-3 | 2 | 5.56% |
| 3-2 | 3-2, 2-3 | 2 | 5.56% |
| 3-3 (double 3) | 3-3 | 1 | 2.78% |
| 4-1 | 4-1, 1-4 | 2 | 5.56% |
| 4-2 | 4-2, 2-4 | 2 | 5.56% |
| 4-3 | 4-3, 3-4 | 2 | 5.56% |
| 4-4 (double 4) | 4-4 | 1 | 2.78% |
| 5-1 | 5-1, 1-5 | 2 | 5.56% |
| 5-2 | 5-2, 2-5 | 2 | 5.56% |
| 5-3 | 5-3, 3-5 | 2 | 5.56% |
| 5-4 | 5-4, 4-5 | 2 | 5.56% |
| 5-5 (double 5) | 5-5 | 1 | 2.78% |
| 6-1 | 6-1, 1-6 | 2 | 5.56% |
| 6-2 | 6-2, 2-6 | 2 | 5.56% |
| 6-3 | 6-3, 3-6 | 2 | 5.56% |
| 6-4 | 6-4, 4-6 | 2 | 5.56% |
| 6-5 | 6-5, 5-6 | 2 | 5.56% |
| 6-6 (double 6) | 6-6 | 1 | 2.78% |
- 6 doubles (each 1/36 probability = 2.78%)
- 30 non-doubles (each 2/36 probability = 5.56%)
- Probability of rolling doubles on any given roll: 6/36 = 16.67% (1 in 6)
How Doubles Work
When you roll two identical numbers (doubles), you play those moves four times instead of twice. Double-3 means you make four moves of 3 pips each. This is what makes doubles so powerful — they’re effectively twice the movement of a non-double roll.
Best and Worst Doubles
| Double | Rating | Why |
|---|---|---|
| 6-6 | Excellent | Move two back checkers across the board; massive pip gain |
| 5-5 | Excellent | Strong home board builder; great from any position |
| 4-4 | Very Good | Makes key points; strong in multiple game types |
| 3-3 | Very Good | Excellent early game point maker |
| 2-2 | Good | Useful home board and mid-game |
| 1-1 | Situational | Weakest double numerically but sometimes makes two key points |
Dice Probability and Its Practical Applications
Hitting Probability
If your opponent has a blot (single checker) and you need to roll a specific number (or combination) to hit it:
| Distance to blot | Combinations that hit | Probability |
|---|---|---|
| 1 pip away | 11 combinations (any die showing 1) | 30.56% |
| 2 pips away | 12 combinations | 33.33% |
| 3 pips away | 14 combinations | 38.89% |
| 4 pips away | 15 combinations | 41.67% |
| 5 pips away | 15 combinations | 41.67% |
| 6 pips away | 17 combinations | 47.22% |
| 7+ pips away | Decreasing | Less than 30% |
Numbers 1–6 can always be hit by a single die. Numbers 7–12 require a specific combined roll (e.g., 9 can be hit by 3-6, 4-5, 6-3, 5-4 = 4 combinations = 11.11%).
Re-entering from the Bar
If you have a checker on the bar, you can only re-enter on your opponent’s home board (points 19–24 from your perspective, or 1–6 from theirs). For each die result, that point must be open (not held by 2+ enemy checkers).
| Points closed by opponent | Probability of entering (1 checker on bar) |
|---|---|
| 0 closed | 100% |
| 1 closed | 30 out of 36 = 83.3% |
| 2 closed | 20 out of 36 = 55.6% |
| 3 closed | 12 out of 36 = 33.3% |
| 4 closed | 6 out of 36 = 16.7% |
| 5 closed | 1 out of 36 = 2.8% (doubles only) |
| 6 closed | 0% — cannot enter |
The Doubling Cube: Not a Die
The doubling cube is often confused with a playing die, but it has no random function. It is a stake multiplier — a six-faced marker numbered 2, 4, 8, 16, 32, and 64 that tracks the current value of the game.
- At game start, the doubling cube is placed in the centre with 64 face-up (meaning the cube is available to either player)
- When a player doubles, they turn the cube to show the new stake (2, then 4, if redoubled, then 8, etc.)
- The cube then belongs to the player who accepted the double — only they can redouble next
- The maximum theoretical value is 64× the original stake
For full details, see the Doubling Cube guide.
Choosing Fair Dice for Serious Play
In casual games, any dice work. For serious or money play, dice quality matters:
What Makes Dice Fair?
- Perfectly cubic — All faces must be equal squares; any deviation makes certain faces more likely to land face-up
- Flush pips — Pips drilled into a face and filled with paint change the weight distribution. The 1-face (one pip drilled) is lighter than the 6-face (six pips drilled); precision dice correct for this
- No interior bubbles — Mass-produced dice often have air bubbles that bias the roll
- Sharp edges — Casino-style precision dice have square edges rather than rounded; rounded edges tend to favour specific faces
Types of Backgammon Dice
| Type | Description | Suitable For |
|---|---|---|
| Casino-grade precision dice | Perfect cubes, flush pips, sharp edges | Serious money and tournament play |
| Quality plastic dice (e.g., Crisloid) | Well-made, reasonably fair | Club and regular home play |
| Standard set dice | Adequate for casual play | Home games, beginners |
| Cheap dice (rounded, unweighted) | Statistically biased | Not recommended |
Frequently Asked Questions
What happens if I roll a die off the board?
If a die (or both dice) leaves the playing surface, both dice must be rerolled. The same applies if a die lands on a checker or is cocked.
Can I roll any time?
No — you can only roll at the start of your turn, after your opponent completes their move and picks up their dice. Rolling out of turn is not valid.
Why do doubles give four moves instead of two?
This is a long-standing rule, not random. Two identical dice are treated as if you rolled that number on four dice simultaneously. It makes doubles exciting and powerful, balancing the game’s risk/reward.
Do I have to use both dice?
Yes, if legally possible. You must use both dice values if you can make a legal move with each. If only one die can be played, you must play it — choosing the higher value if only one of the two is playable.
Are online dice truly random?
Reputable platforms use certified server-side random number generators (RNGs). There is no credible evidence of systemic dice bias on major platforms like Backgammon Galaxy or FIBS.
Further Reading
- Backgammon Probability — Deep dive into backgammon odds and probability
- Backgammon Rules — Complete rules reference including all dice rules
- Backgammon Equipment Guide — Choosing the right dice, cups, and board
- Doubling Cube Strategy — How the cube works and when to use it
- How to Play Backgammon — Full beginner’s guide