Dice Roller
Choose how many dice and how many sides, then roll.
Dice notation
Board games and tabletop roleplaying games describe rolls as NdS: N dice with S sides each. 2d6 means two six-sided dice, 1d20 means one twenty-sided die, and 3d8 means three eight-sided dice. Set the two fields to match and the roller adds up the total for you. Each die is rolled independently, so every face is equally likely on every roll.
Rolling two six-sided dice
Totals from two dice are not equally likely. There are six ways to make 7 and only one way to make 2 or 12, which is why 7 comes up most often.
| Total | Ways to roll it | Chance |
|---|---|---|
| 2 | 1 of 36 | 2.8% |
| 3 | 2 of 36 | 5.6% |
| 4 | 3 of 36 | 8.3% |
| 5 | 4 of 36 | 11.1% |
| 6 | 5 of 36 | 13.9% |
| 7 | 6 of 36 | 16.7% |
| 8 | 5 of 36 | 13.9% |
| 9 | 4 of 36 | 11.1% |
| 10 | 3 of 36 | 8.3% |
| 11 | 2 of 36 | 5.6% |
| 12 | 1 of 36 | 2.8% |
This is why a game that wants results to cluster around the middle uses two smaller dice, and one that wants every result equally likely uses a single larger die. 2d6 and 1d12 cover similar ranges but behave very differently.
Common dice
| Die | Range | Average roll | Chance of the top number |
|---|---|---|---|
| d4 | 1 to 4 | 2.5 | 25.0% |
| d6 | 1 to 6 | 3.5 | 16.7% |
| d8 | 1 to 8 | 4.5 | 12.5% |
| d10 | 1 to 10 | 5.5 | 10.0% |
| d12 | 1 to 12 | 6.5 | 8.3% |
| d20 | 1 to 20 | 10.5 | 5.0% |
| d100 | 1 to 100 | 50.5 | 1% |
The average of NdS is N × (S + 1) ÷ 2, so 3d6 averages 10.5 and 2d20 averages 21.