Twenty-One Dice Game: Rules, Bust Odds and When to Stop
Twenty-One is a dice version of the card game of the same name. You roll one die again and again and add up the numbers, trying to get as close to 21 as you can without going over. Stop too early and someone beats you; roll once too often and you go bust. It takes a minute to learn, works for any number of players, and makes a good lesson in adding and in risk.
What You Need
- One six-sided die (or our Dice Roller set to one die).
- Paper and a pencil, or just good memory for short games.
- Two or more players.
Who Goes First
Going last is an advantage, because you can see the totals you have to beat. So pick the first player fairly: everyone rolls one die with the Dice Roller and the highest roll starts, or spin our Random Name Picker. In a game of several rounds, the first player moves one seat to the left each round.
How to Play
- Roll and add. On your turn, roll one die and keep a running total.
- Roll again or stop. After each roll, decide whether to roll again or stop and keep your total.
- Over 21 is bust. If your total goes over 21, you are out of this round.
- Highest total wins. When everyone has played, the highest total of 21 or less wins the round. Players with the same total roll off.
- Keep score. Give one point to the winner of each round, and play to 5 or 10 points.
House rules differ. Some groups start each turn with two dice and then roll one die at a time; others have one player act as the “dealer” who must roll until reaching 17. Agree on the rules before the first round.
Your Chance of Going Bust
With one die, you can only go bust from 16 or more. In the table, “Your total” is where you are now and “Bust on next roll” is the exact chance that one more roll takes you over 21.
| Your total | Bust on next roll |
|---|---|
| 15 or less | 0% |
| 16 | 17% (1 in 6) |
| 17 | 33% (2 in 6) |
| 18 | 50% (3 in 6) |
| 19 | 67% (4 in 6) |
| 20 | 83% (5 in 6) |
At 18 the next roll is a coin flip between safe and bust. At 20 only a 1 saves you.
When Should You Stop?
What if you decide in advance to stop at a set total? We worked out the exact results for each target. “Stop at” is the total where you stop rolling, “Bust” is how often that plan goes over 21, “Exactly 21” is how often it lands on 21, and “Beat a 17 player” is how often it wins outright against one opponent who always stops at 17 (the rest are ties and losses).
| Stop at | Bust | Exactly 21 | Beat a 17 player |
|---|---|---|---|
| 16 | 0% | 5% | 29% |
| 17 | 5% | 10% | 40% |
| 18 | 14% | 14% | 51% |
| 19 | 29% | 19% | 52% |
| 20 | 48% | 24% | 43% |
| 21 | 71% | 29% | 26% |
Against that opponent, stopping at 18 or 19 works best: you win about half the time. Stopping at 21 lands on 21 more often but goes bust nearly three times in four. For the maths behind numbers like these, see our dice probability guide.
Tips
- Know the number to beat. If you play after others, roll until you beat the best total so far, then stop. If nobody is left standing, stop as soon as you are safe.
- Playing first? Aim for 18 or 19. You cannot see what others will get, so a solid total is better than a perfect one.
- Do not roll from 20. Only a 1 helps, so five times in six you go bust.
- Make it a maths game. Young players say the new total out loud after every roll. Older ones can work out the bust chance before they roll.
Variations
- Two-dice start: roll two dice for your first roll, then one die at a time. Turns are quicker.
- Dealer game: one player is the dealer and must keep rolling below 17 and stop at 17 or more. Everyone else tries to beat the dealer.
- Different target: play to 31 or 50 for longer turns and more adding practice.
- Team Twenty-One: two teams take turns, and teammates discuss whether to roll again.
Enjoy deciding when to stop? Pig and Skunk are built around the same choice. You will find more games in our list of easy dice games.
Where the Game Comes From
Dice Twenty-One borrows its goal from the card game Twenty-One, better known today as blackjack, which has been played for centuries. Dice versions are simple folk games with many house rules, and we could not find a reliable record of who first played Twenty-One with dice.
FAQ
How do you play Twenty-One with dice?
Roll one die again and again and add up the numbers. Stop whenever you like. If you go over 21 you are bust. After everyone has played, the highest total of 21 or less wins.
When should you stop in dice Twenty-One?
If you go first, stopping at 18 or 19 is a good plan. If you go later, keep rolling until you beat the best total so far.
What are the odds of going bust from 18?
From 18, a 4, 5 or 6 takes you over 21, so the chance of going bust on the next roll is 3 in 6, or 50%.
Is dice Twenty-One the same as blackjack?
It uses the same goal of 21, but with a die instead of cards. There are no card values or aces to worry about, which makes it easier for children.
Can you play Twenty-One with an online die?
Yes. Set our free Dice Roller to one die and keep the running total on paper.