Single die
Roll a d12
A 12-sided die, rolled in your browser. Every face has an equal 8.33% chance, which works out to 1 in 12.
The odds on a d12
A single die is flat: no total is more likely than any other. The curve only appears once you roll more than one, which is what the odds calculator is for.
- Lowest
- 1
- Highest
- 12
- Average
- 6.50
- Each face
- 8.33%
- Odds
- 1 in 12
Every bar the same height. That flatness is the whole point of a single die: 8.33% per face, no favourites.
What a d12 is for
Greataxe damage and barbarian hit dice. The least used die in most campaigns, and the most satisfying when it lands high.
The most neglected die in the bag
Most players finish a campaign having rolled the d12 fewer than a dozen times. There is one common weapon that uses it and one class feature, and if your table has neither, the dodecahedron sits in the tray looking decorative for months.
That is a shame, because it is the most dramatic die in the set. A twelve point swing on a single roll means a greataxe can deal less than a dagger or more than a heavy crossbow crit, and there is no way to predict which. The average of 6.5 is barely better than a d10's 5.5, so mathematically the axe is a marginal upgrade; what you are actually buying is variance. Some tables love that and some find it maddening, and the argument recurs on every forum where weapon damage comes up.
Where it does get interesting is on a critical hit, which doubles the dice to 2d12, and again with the barbarian feature that adds a third to reach 3d12. Two dice already pull the shape into a triangle; three make it a proper curve averaging 19.5.
Hitting a target number
What a flat d12 beats, and how much two-dice advantage moves it.
| Need | Flat | Advantage | Disadvantage |
|---|---|---|---|
| 2+ | 91.7% | 99.3% | 84.0% |
| 3+ | 83.3% | 97.2% | 69.4% |
| 4+ | 75.0% | 93.8% | 56.2% |
| 5+ | 66.7% | 88.9% | 44.4% |
| 6+ | 58.3% | 82.6% | 34.0% |
| 7+ | 50.0% | 75.0% | 25.0% |
| 8+ | 41.7% | 66.0% | 17.4% |
| 9+ | 33.3% | 55.6% | 11.1% |
| 10+ | 25.0% | 43.8% | 6.25% |
| 11+ | 16.7% | 30.6% | 2.78% |
| 12+ | 8.33% | 16.0% | 0.694% |
How to use this roller
Tap the die or press the roll button. To roll several at once, change How many, and the chart above redraws to the distribution you are actually rolling. To add a bonus, put it in Modifier: entering 3 turns a d12 into 1d12+3. Negative numbers work for penalties. The keyboard shortcut is R. After a roll, Copy link gives you a URL that shows exactly that result to whoever opens it.
Nothing is stored on a server and no account is needed. The page works offline once loaded, which matters if the venue has poor signal.
Common questions about the d12
What are the odds of rolling a 12 on a d12?
The odds of rolling a 12 on a d12 are exactly 8.33%, or 1 in 12. Every face on a fair d12 is equally likely, so a 12 is no rarer than any other number.
Is a d12 better than 2d6?
Not on average: 2d6 averages 7 and a d12 averages 6.5. The real difference is the spread. A d12 rolls 3 or less 25% of the time against 8.33% for 2d6, and it rolls 10 or more 25% of the time against 16.7%. The d12 is the gamble, 2d6 is the steady choice, which is the whole greataxe against greatsword argument in two numbers.
What can you roll instead of a d12?
Roll a d6 and flip a coin: on heads, add 6. Every result from 1 to 12 then has exactly a 1 in 12 chance. Rolling 2d6 does not work as a substitute, because 2d6 can never show 1 and lands on 7 six times as often as it lands on 12.
What is the average roll on a d12?
The average roll on a d12 is 6.5. That is the midpoint of 1 and 12, and the average of any die is always (sides + 1) divided by 2. Over many rolls your results converge on it, but any single roll tells you nothing.