D8 Roller
Roll a virtual d8 — an octahedron — two four-sided pyramids base to base, with opposite faces summing to 9. Every face lands with an equal 1-in-8 probability and an average roll of 4.5, generated with cryptographic randomness in your browser. The d8 is two pyramids joined at the base, giving eight triangular faces that read cleanly from the top. It sits in the sweet spot of the polyhedral set: a wider spread than a d6 without the swinginess of a d20, which is why so many weapon tables land on it.
D8 Roller reference last updated · reference source
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Dated static reference; no live data is fetched. Verify current source values and assumptions before relying on results.
What this tool does
Roll a virtual d8 — an octahedron — two four-sided pyramids base to base, with opposite faces summing to 9. Every face lands with an equal 1-in-8 probability and an average roll of 4.5, generated with cryptographic randomness in your browser. The d8 is two pyramids joined at the base, giving eight triangular faces that read cleanly from the top. It sits in the sweet spot of the polyhedral set: a wider spread than a d6 without the swinginess of a d20, which is why so many weapon tables land on it.
How to use the D8 Roller
- Check Sides per die: 8.
- Check Dice count: 1.
- Review the D8 Roller result and its exact-value comparison table.
- Verify assumptions before applying the result.
Formula
each die is a uniform integer from 1 through sides, using Web Crypto
- sides
- Sides per die
- count
- Dice count
Independent virtual dice. Generate again to reroll.
Worked example
D8 Roller: Sides per die = 8; Dice count = 1. Roll a virtual d8 — an octahedron — two four-sided pyramids base to base, with opposite faces summing to 9. Every face lands with an equal 1-in-8 probability and an average roll of 4.5, generated with cryptographic randomness in your browser. The d8 is two pyramids joined at the base, giving eight triangular faces that read cleanly from the top. It sits in the sweet spot of the polyhedral set: a wider spread than a d6 without the swinginess of a d20, which is why so many weapon tables land on it.
Inputs
- Sides per die8
- Dice count1
Result
- Total8
- Rolls8
- Expected total (average over many rolls)4.5
- Minimum possible total1
- Maximum possible total8
- Chance of the maximum total12.5%
- Chance each single die shows its top face12.5%
D8 quick odds
| Question | Answer |
|---|---|
| Average roll | 4.5 |
| Chance of any single face | 1 in 8 (12.5%) |
| Chance of rolling the maximum (8) | 1 in 8 |
| Chance of rolling above the average (over 4.5) | 4 in 8 (50%) |
| Faces | 8 |
Results explained
- Total
- The sum of the independent d8 rolls shown, each a uniform integer from 1 to 8.
- Rolls
- The individual die results in the order rolled.
- Expected total (average over many rolls)
- Dice count × 4.5, the theoretical average for a d8.
- Chance of the maximum total
- The probability that every die in the roll shows 8 at once: (1/8)^count.
Frequently asked questions
In Dungeons & Dragons the d8 is the longsword, battleaxe and rapier damage die, the hit die for bards, clerics, druids, monks, rogues and warlocks, and the workhorse for mid-tier spell damage. Many skirmish war games use it for morale and artillery scatter checks.
(8 + 1) ÷ 2 = 4.5. Every face from 1 to 8 is equally likely, so the long-run average sits exactly halfway between the minimum and maximum.
Exactly 1 in 8, or 12.5%, on a single die. With two dice both showing 8 the chance drops to 1 in 64 (1.563%).
Yes. Rolls come from the Web Crypto API with rejection sampling, so no face is favoured by modulo bias, and nothing is weighted, seeded from the clock or influenced by previous rolls.
Rolling two d8s ('2d8') averages 9 — exactly one more than a single d16 would if it existed — and designers use 2d8 when they want a bell curve centred where a longsword 'should' land.
Yes — raise the dice count (gamers write that as 2d8, 3d8 and so on). Totals then follow a bell curve centred on 4.5 per die: extremes get rarer as you add dice, which is why multi-dice rolls feel more predictable than a single big die.