Dice Roller
How it works
Rolling physical dice is impractical when you don't have them to hand, when you need dice with unusual face counts (a d10, d12, or d20), or when you want a logged history of results. The Dice Roller simulates any combination of standard tabletop dice — d4, d6, d8, d10, d12, d20, and d100 (percentile) — with a single click, running entirely in your browser with cryptographically strong randomness.
**Dice notation** Tabletop gaming uses standard notation: NdX, where N is the number of dice and X is the face count. 2d6 = roll two six-sided dice and add them. 1d20 = roll one twenty-sided die. 3d8+5 = roll three eight-sided dice, add them, then add 5 (a modifier). The roller parses standard NdX+M notation and displays individual die results alongside the total.
**Probability distributions** A single die produces a uniform distribution — each face is equally likely. Multiple dice produce a bell-curve (binomial) distribution: with 2d6, totals near 7 are most probable (6 ways to make 7), while totals of 2 and 12 are least likely (1 way each). This is why Dungeons & Dragons character ability scores (4d6 drop lowest) are statistically higher than 3d6 straight — the bell curve of multiple dice shifts the distribution.
**Statistical context** With 2d6: expected value = 7.0; standard deviation ≈ 2.42. With 4d6 drop lowest: expected value ≈ 12.24. The roller's history log lets you verify the distribution over many rolls — useful for statistics demonstrations and game design testing.
**Custom face counts** Need a d3 (possible from a d6: 1-2=1, 3-4=2, 5-6=3) or a d7? The roller supports any face count from 2 to 1000, enabling probability experiments with non-standard distributions.
Privacy: all random number generation uses the browser's `crypto.getRandomValues()` API. No dice results are transmitted.
Frequently Asked Questions
- This tool uses `crypto.getRandomValues()` — the browser's cryptographically secure pseudo-random number generator backed by OS entropy sources (hardware events, timing jitter). Physical dice are approximately fair but are affected by surface imperfections, technique, table surface, and boundary conditions — research has shown physical dice bias of 0.1–0.5% per face. The digital tool produces a statistically perfect distribution over large sample sizes.
- NdX is standard tabletop RPG dice notation: N = number of dice, X = number of faces per die. 2d6 = roll two 6-sided dice and add them (range 2–12). 1d20 = one 20-sided die (range 1–20). 4d6 = four 6-sided dice (range 4–24). You can add modifiers: 1d20+5 means roll 1d20 and add 5 to the result. The 'd' stands for 'die' or 'dice'.
- A single die produces a flat (uniform) distribution — each face equally likely. With 2d6, totals near 7 are more likely because there are more ways to make them: 6 ways to make 7 (1+6, 2+5, 3+4, 4+3, 5+2, 6+1), but only 1 way to make 2 (1+1) or 12 (6+6). With more dice, the Central Limit Theorem applies: the sum of independent uniform distributions converges to a normal (bell-curve) distribution. This is why 4d6 ability scores in D&D tend to cluster around 12–14.
- A d100 (percentile die) generates values from 1 to 100. In tabletop RPGs, this is often simulated with two d10s: one representing tens digits (00–90) and one representing units (0–9). Reading '00' on the tens die and '0' on the units die typically means 100 (or sometimes 0, depending on system). A digital d100 is simpler — it directly generates an integer from 1 to 100 with equal probability.