What is a dice roller?
A dice roller simulates rolling physical dice. You pick how many dice, how many sides each die has, and you get back the results plus the total. Same role a fistful of dice plays in a tabletop game or a board game, just without the dice rolling off the table and getting lost under the couch.
Physical dice are great, but they have practical limits. You need a flat surface. You need to own dice in the right shape — a d20 isn't sitting in most kitchen drawers. You need to add up totals by hand, which gets tedious when you're rolling 8d6 for a fireball. The Dice Roller handles all of that. Pick the configuration, hit roll, get the answer. Roll again. The dice never go missing and the math is never wrong.
The roller supports the standard polyhedral set used in tabletop RPGs and most board games: d2 (a coin in dice form), d4, d6, d8, d10, d12, d20, and d100 (percentile). You can roll any number of each, all at once.
How to use the Dice Roller
Open the Dice Roller and pick your configuration.
- Choose the type of die — d2, d4, d6, d8, d10, d12, d20, or d100
- Set how many of that die to roll (1 to whatever you need)
- Hit roll
- Read each individual die result, plus the total at the bottom
- Roll again — fresh results every time, with no memory of previous rolls
The roller uses crypto.getRandomValues(), the browser's cryptographically-secure random number generator. Each roll pulls fresh entropy from the operating system; there's no pattern to predict and no seed that could be reverse-engineered. As fair as any physical die you've used, and almost certainly fairer than the worn-down d20 sitting in your dice bag.
The dice and what they're for
Different dice exist because different games need different probability distributions. Here's the standard set, what each one looks like, and what people roll it for:
| Die | Shape | Range | Common uses |
|---|---|---|---|
| d2 | Coin (or any 2-sided pick) | 1–2 | Coin flips, binary choices. Functionally identical to the Coin Flip. |
| d4 | Tetrahedron (caltrop) | 1–4 | D&D dagger damage, light weapons, small choices among 4 options. |
| d6 | Cube | 1–6 | Monopoly, Yahtzee, Settlers of Catan, most board games. The most common die in human history. |
| d8 | Octahedron | 1–8 | D&D longsword damage, medium weapons. Less common in non-RPG games. |
| d10 | Pentagonal trapezohedron | 1–10 (or 0–9) | D&D shortbow damage. Two d10s together (one as "tens," one as "ones") generate a d100 percentile roll. |
| d12 | Dodecahedron | 1–12 | D&D greataxe damage, barbarian hit dice. The forgotten die. |
| d20 | Icosahedron | 1–20 | D&D attack rolls, skill checks, saving throws. The signature die of modern RPGs. |
| d100 | Pair of d10s, or a single 100-sided die | 1–100 | RPG percentile checks, random encounter tables, "what loot drops?" rolls. |
The d6 is by far the most common die outside RPGs. Almost every classic board game uses 1, 2, or 3 of them. The d20 is the signature die of Dungeons & Dragons and the d20 system (Pathfinder, Starfinder, dozens of indie RPGs). The d100 is a workhorse for any game that wants a "roll under 100" percent check.
The math of 2d6: why dice totals aren't uniform
Roll one d6 and you get 1, 2, 3, 4, 5, or 6, each with exactly 1/6 probability. Flat distribution. Boring, in a good way.
Roll two d6 and add them up. You'd think the results 2 through 12 would each be equally likely. They aren't. There's only one way to get a total of 2 (1+1) and one way to get a total of 12 (6+6). But there are six different ways to get a total of 7 (1+6, 2+5, 3+4, 4+3, 5+2, 6+1). So 7 is six times more likely than 2 or 12.
This is why rolling 2d6 produces a triangular distribution centered on 7. It's the foundational math behind Settlers of Catan (where 6 and 8 are the most valuable resource numbers because they're hit most often) and craps (where 7 ends the round because it's the most common roll).
Worked example. You roll 4d6 to generate a D&D ability score. Here's the actual roll we got:
Roll: 4d6 → 5, 3, 6, 2 → Total: 16
In standard D&D character generation, you drop the lowest die and sum the rest. Drop the 2; keep 5+3+6 = 14. That's a respectable ability score — average is about 12.
The more dice you add together, the more the total tightens around the average. 1d6 has a flat distribution. 2d6 has a triangle. 3d6 has a smooth bell curve peaking at 10–11. By the time you're rolling 10d6, the results are normally distributed and almost always come out between 25 and 45 (the theoretical range is 10 to 60, but the extremes happen roughly once in 60 million rolls).
This matters for game design and for picking the right roll for the situation. If you want high variance — a "swingy" outcome where anything could happen — use one big die (d20, d100). If you want consistency around an average — a roll where extreme results are rare — use lots of small dice (3d6, 4d6).
D&D and the d20 system
If you've ever played Dungeons & Dragons, you've rolled a d20 hundreds of times. The d20 system uses the same basic mechanic for almost every uncertain action:
- Roll a d20
- Add a modifier (your character's bonus for that thing)
- Compare the total to a target number (the difficulty class, or DC)
- If total ≥ DC, you succeed. If less, you fail.
The flat distribution is the whole point. Every result from 1 to 20 is equally likely, so a low-skilled character can occasionally roll a 20 and pull off something heroic, and a high-skilled character can occasionally roll a 1 and faceplant. The variance creates story. Bell-curve systems (which exist — GURPS uses 3d6) produce more predictable outcomes but less narrative tension.
Worked example. You're attacking a goblin in a D&D game. Your attack bonus is +5; the goblin's armor class is 15.
- You roll the Dice Roller for 1d20. Result: 12.
- Total: 12 + 5 = 17.
- 17 ≥ 15, so you hit. Now roll damage: 1d8 for a longsword → 6. Goblin takes 6 damage.
The Dice Roller doesn't know about D&D rules — it just gives you the random numbers. You do the modifier math. That's the right division of labor; a dice roller that tried to handle every RPG's rules would be ten times more complicated and useful for nothing else.
Board games and the d6
If you're playing Monopoly, Risk, Catan, Yahtzee, or Backgammon, you're rolling d6s. The Dice Roller handles all of these — set the die type to d6 and the count to however many your game needs.
- Monopoly — 2d6 per turn. Move that many spaces. Doubles let you roll again (until 3 in a row, which sends you to jail).
- Yahtzee — 5d6, with selective rerolling. The Dice Roller can roll all 5 at once; you'd manage the reroll logic in your head or on a scorecard.
- Catan — 2d6 per turn. Resources are produced based on the result. 7 has a special effect (move the robber).
- Risk — attacker rolls up to 3d6, defender rolls up to 2d6. Compare highest dice in pairs.
- Backgammon — 2d6 per turn, sometimes used as two separate moves. Doubles give 4 moves at that value.
If your physical dice are lost or the cat ate them, the Dice Roller is a clean substitute. It's also useful for solo play where you're testing a game's mechanics without setting up the whole table.
Percentile rolls and random tables
The d100 — or "percentile dice" — is the workhorse of any game with random tables. Roll once, get a number from 1 to 100, look it up on a table to see what happens.
Worked example. A classic D&D random encounter table might look like:
| d100 roll | Encounter |
|---|---|
| 01–20 | Nothing — empty forest |
| 21–50 | A pack of wolves (3d4 of them) |
| 51–75 | A traveling merchant with goods to trade |
| 76–90 | A goblin scouting party (1d6 goblins) |
| 91–99 | An ancient ruin in a small clearing |
| 100 | A dragon. Run. |
The Dice Roller rolls the d100 for you. You read the result, look up the entry, and the dungeon master narrates the encounter. The "00" or "100" on the high end is the rare result (1% chance), which is exactly the point — it's where the most dramatic outcomes get parked.
Related randomness tools
The Dice Roller covers any situation where you need a random number in a known range. For other random-decision needs:
- Coin Flip — when you need a binary 50/50. Functionally a d2, but cleaner to use for yes/no calls.
- List Randomizer — paste a list, get it back shuffled. Useful when "random number 1–8" doesn't capture what you actually need.
- Random Name Picker — pick one item from a list. The single-winner case.
- Team Generator — split a list of people into random balanced teams.
- Random Word Generator — for word-based prompts (creative writing, party games).
Frequently asked questions
Is this Dice Roller really fair?
Yes. Each roll uses crypto.getRandomValues(), the browser's cryptographically-secure random number generator. Each face of each die has exactly equal probability. There's no bias toward any number, no "hot" or "cold" dice, no memory of previous rolls.
Why does the Dice Roller sometimes give the same number twice in a row?
Because it's random. Rolling a 4 on a d6 has a 1/6 probability. The next roll also has a 1/6 probability of being a 4. The dice don't remember. If you roll 100 times you should see plenty of back-to-back matches — they're not glitches, they're the math working.
What's the difference between rolling 2d6 and 1d12?
Both give you a range of possible values, but the distribution is very different. 1d12 gives you 1 through 12 with equal probability (1/12 each). 2d6 gives you 2 through 12, with 7 being the most likely (1/6) and 2 and 12 being the least likely (1/36 each). Choose 1d12 when you want every outcome equally likely; choose 2d6 when you want results clustered around the middle.
Can I roll dice with non-standard numbers of sides (like d3 or d7)?
Not directly — the Dice Roller sticks to the standard set (d2, d4, d6, d8, d10, d12, d20, d100). To simulate a d3, roll a d6 and divide the result by 2 (rounded up): 1–2 = 1, 3–4 = 2, 5–6 = 3. For a d7, roll a d8 and reroll any 8s. Most TTRPGs use the standard set deliberately; if you need exotic dice often, you might want a more specialized rolling tool.
Does the order of dice matter when I roll multiple?
No. The Dice Roller shows individual results because that's useful information (D&D character creation drops the lowest die, Yahtzee cares about which face is which, etc.), but the underlying randomness doesn't care about order. Rolling 3d6 and getting 4, 2, 6 is the same outcome as getting 6, 4, 2 in any context where you only care about the total or the set.
Can I use the Dice Roller offline?
Yes, once the page is loaded. The randomness runs entirely in your browser — no server call, no network dependency, nothing leaves your device. Useful when you're playing a board game with friends in a basement or a backyard with bad reception.
Why does my D&D group still use physical dice if a digital roller is fairer?
Because rolling dice is part of the ritual. The physical clatter is the sound of the game. The dice are an extension of the character — players name them, decorate them, accuse them of betraying them. A digital roller is more accurate but less fun. The Dice Roller is useful when you don't have your dice with you, when you want to verify a result, or when you're playing remotely. For most in-person tabletop sessions, the physical dice win every time.