Our dice are fair
"The dice are rigged" is the number one complaint about backgammon sites around the world. Here's exactly how it works on our site, and how you can check for yourself.
How each roll is generated
- Each die is generated by the browser's secure random number generator, the same mechanism used for encryption. Each number from 1 to 6 has an equal chance.
- The dice have no "plan": no special dice for the computer, for levels or for dramatic moments. The computer doesn't know in advance what will come up.
- The dice don't know who staked coins, who is winning or who bought anything. No code changes them: not for those who pay, not against those who win, and not to make you buy. In a game for coins the house fee is fixed and known in advance, 10% of the pot, and has nothing to do with the dice.
- When playing with a friend, each roll is generated on the roller's device and sent to the other. Later we'll also add verification of the rolls through the server.
We tested it: 10 million rolls
We ran 10 million rolls of the exact same function that rolls the dice on the site, and checked them with standard statistical tests:
| What we checked | Expected | What we got |
|---|---|---|
| Each number, 1 to 6 | 16.67% | 16.65%–16.68% |
| Doubles | 16.67% | 16.675% |
| Doubles right after doubles | 16.67% | 16.659% |
| Chi-square test for the numbers | Below 11.07 | 6.92 |
| Chi-square test for the 21 roll types | Below 31.41 | 16.20 |
| Longest streak of doubles | About 9 | 9 |
The function gets no information about the game: not who's leading, not who's on the bar and not who's playing. The rolling animation is decoration, and the result is decided before it starts.
Why it sometimes feels rigged
True randomness produces streaks, and the brain remembers the opponent's lucky rolls and forgets ours. Some numbers:
| What | Chance |
|---|---|
| Any doubles in a roll | 1 in 6 (16.7%) |
| A specific double, e.g. double sixes | 1 in 36 (2.8%) |
| At least one doubles roll in 6 rolls | 67% |
| Two doubles in a row for the same player, during one game | About once every two games |
| Hitting a lone checker 6 away (nothing blocking the way) | 17 in 36 (47%) |
| Entering from the bar when only one point is open | 11 in 36 (31%) |
In one game each player rolls about 25–30 times, so even "rare" things happen all the time.
Check for yourself
The site counts every roll on your device, across all your games. At the end of a game, on the analysis screen, under "Dice", you can see how many times each number came up and how many doubles there were (from 20 rolls up). After a few hundred rolls, each number comes up about a sixth of the time, and doubles about once every six rolls.