Roll D8
One eight-sided die, numbered 1 to 8. Each face is 12.5%, which is one in eight, and the average roll is 4.5. The octahedron shape changes none of that.
1d8 —
Press roll.
Lowest possible 1, highest 8, average 4.5.
One in eight, every time
Eight faces, 12.5% each, average 4.5. A d8 is one of the friendlier dice to estimate with, because 12.5% is easy to double: any two faces are 25%, any four are 50%. Rolling 5 or better is 50%.
Eight rolls, eight different numbers? Almost never
People expect eight rolls to sweep the die. The chance of all eight faces appearing once each in eight rolls is 0.24%, or one time in 416. The realistic picture:
| Question | Answer |
|---|---|
| Repeat within three rolls | 34.4% |
| A given face still missing after ten rolls | 26.3% |
| Rolls needed on average to see all eight | about 22 |
Duplicates are the normal texture of a small die. Three 6s in a row is a 1 in 64 event on any given stretch, and across an evening of rolling you should expect to hit something like it.
What a d8 is for
- Hit dice and one-handed weapon damage in fifth edition, where 1d8 is the workhorse.
- Compass directions: north, north-east, east and so on, eight of them, one die.
- Any eight-item choice where you want each option to be genuinely equal.
For the same flat 12.5% without dice, use a random number from 1 to 8. Step up a size with the d10, or set your own in the dice roller.