Shut the Box rules: how to play and score
Shut the Box is a dice game for one or more players, played with a box of tiles numbered 1 to 9 and two dice. You roll, close tiles that add up to the throw, and keep going until a throw cannot be played; the tiles still open are your score, and the lowest score wins. This page covers the standard rules, scoring, the common variants and what the exact solution of the game says about strategy.
What you need
- A Shut the Box: a tray with nine tiles numbered 1 to 9 that can be flipped down or slid shut.
- Two ordinary six-sided dice.
- One or more players, and paper for the scores if you play several rounds.
The game is also known as Canoga or Klackers. The rules below are the most common ones; the variants section covers the rest.
The goal
Close as many tiles as you can. When your turn ends, you add up the tiles that are still open, and that sum is your score. The lowest score wins. If you close every tile, you have shut the box: a score of zero, the best result there is.
How a turn works
- 1.Start with all nine tiles open.
- 2.Roll both dice and add them together.
- 3.Close any open tiles whose numbers add up to exactly that total. A throw of 8 on a full box can close the 8, or 1 and 7, 2 and 6, 3 and 5, 1 and 2 and 5, or 1 and 3 and 4.
- 4.Roll again. Closed tiles stay closed for the rest of your turn.
- 5.Your turn ends when you roll a total that no combination of open tiles can make, or when every tile is closed.
The sum must be exact, and if a throw can be played, you must play it. The only choice you have is which tiles to close, and that choice is the whole game: it decides which totals you can still use later.
An example turn
| Throw | You close | Still open |
|---|---|---|
| 5 + 4 = 9 | 9 | 1 2 3 4 5 6 7 8 |
| 6 + 6 = 12 | 4 and 8 | 1 2 3 5 6 7 |
| 2 + 1 = 3 | 3 | 1 2 5 6 7 |
| 6 + 5 = 11 | 5 and 6 | 1 2 7 |
| 4 + 4 = 8 | 1 and 7 | 2 |
| 3 + 5 = 8 | nothing fits | 2 |
The turn ends with only the 2 open, so the score is 2.
Scoring and winning
Your score is the sum of the tiles left open. A turn that ends with 3, 4 and 9 open scores 16. A shut box scores 0.
With several players, each player plays one full turn in order, and the box is reset between players. The lowest score wins the round, and equal scores share it. In many house rules a player who shuts the box wins the round at once. Many tables play a fixed number of rounds and add the scores up, and the lowest total wins.
Common variants
- One die at the end: once the 7, 8 and 9 are all closed, many tables let you choose to roll a single die. Some allow it instead when the open tiles add up to 6 or less. It helps a little: in our calculation, perfect play with the first version averages 11.01 instead of 11.16.
- Dice or total: an older rule only lets you close the tile of the total, or the two tiles matching each die. A throw of 3 and 5 then closes the 8, or the 3 and the 5, and nothing else.
- Bigger boxes: boxes with tiles 1 to 10 or 1 to 12 are played the same way. More tiles mean higher scores, and shutting the box becomes rarer.
- Reading the tiles as a number: instead of adding the open tiles, some tables read them as digits, so 2, 3 and 7 left open scores 237. This makes the lowest tiles the most expensive to leave, which changes the strategy completely.
Agree on the variant before you start. All figures on this page are for the standard rules: tiles 1 to 9, two dice on every throw, and any combination that makes the total.
Strategy from the solved game
With two dice on every throw, the classic box has only 512 possible positions, so the game can be solved exactly by computer. Played perfectly, to keep the expected final score as low as possible, a round scores 11.16 on average. The best possible chance of shutting the box is 7.14 percent, about one round in 14. About half of all perfectly played rounds end on 10 or less, so a score around 10 is normal, not a failure.
What the solution says about your choices:
- On a full box, play a throw of 2 to 9 as the single tile with that number. Closing the 7 beats closing 3 and 4.
- On a full box, play 10, 11 and 12 as the 9 plus a small tile: 1 and 9, 2 and 9, 3 and 9.
- In general, close the high tiles first and use as few tiles as you can. Only 10 of the 36 dice combinations make 9 or more, so a high tile left open is hard to close later and costs the most if the turn ends. This simple rule averages 11.37, close to perfect play.
- Luck matters, but so do choices: a player who picks any legal move at random averages about 20.4.
Playing in Shut the Box Challenge
EU Studio's Shut the Box Challenge for iPhone and iPad plays the standard rules: tiles 1 to 9, two dice on every throw, any combination of open tiles that makes the total, and the sum of the open tiles as the score. Lowest score wins, and equal scores are a draw. The one-die rule is not offered, because in every mode other players get exactly your throws, and choosing how many dice to roll would change which throws come next. Tiles that cannot be used for the current throw are dimmed.
- Computer: the computer plays the same throws as you, in the same order, after you. Easy picks an arbitrary legal move, Medium closes the high numbers first, and Hard always chooses the move with the lowest expected final score, which is the perfect play described above. Its result stays hidden until your round is over.
- Daily Dice: one set of dice a day, the same for everyone, with one official attempt and a streak for every day in a row.
- Friend Box: send your round's throws to a friend as a link or a code. They play the same dice blind, or with your finishing position as the target.
- Solo: just you and the box. You can ask for the best move, which aims first for the highest chance of shutting the box and then for the lowest expected score.
After a round, the game shows how many of your choices could have been better and what they cost, measured against the exact solution on the dice you actually had.
Questions about the rules
- What happens when you shut the box?
- You have closed all nine tiles and score zero, the best possible result. In many house rules a player who shuts the box wins the round at once, whatever the others score.
- When can you roll only one die in Shut the Box?
- Only if your table plays that variant. The most common version allows one die once the 7, 8 and 9 are all closed; others allow it when the open tiles add up to 6 or less. In the standard rules you always roll two dice.
- Do you close the total or each die separately?
- In the standard rules you close any combination of open tiles that adds up to the total, so a 3 and a 5 can close the 8, or 3 and 5, 1 and 7, 2 and 6, and so on. An older variant allows only the tile of the total or the two tiles matching the dice.
- What is a good score in Shut the Box?
- Anything under 10 is a good round. Even perfect play averages 11.16 on the classic box, and only about half of perfectly played rounds end on 10 or less.
- How often can you shut the box?
- With perfect play, 7.14 percent of the time on the classic box with two dice, or about one round in 14. Most players manage it less often.
- Is Shut the Box luck or skill?
- Both. The dice decide a lot, but a player who picks a random legal move every time averages about 20.4, while perfect play averages 11.16.
