Dice Roller

Dice Roller rolls up to twelve dice at once, from a four-sided die to a hundred-sided one, with an optional modifier added to the total. Six-sided dice are drawn with pips, the way a real die looks; the others show their number, because a twenty-sided die drawn with pips would be unreadable.

The randomness is the part that matters. The numbers come from the browser's cryptographic random source with rejection sampling, not from taking a remainder of a random value. Taking a remainder is the obvious shortcut and it very slightly favours the lower faces — invisible in a single game, and still the wrong thing to ship on a page whose only job is to be fair. Rejection sampling discards the handful of values that would cause the bias and draws again, so every face is exactly equally likely.

The message under each roll gives the possible range and the average for the dice you chose, which is the context that makes a result meaningful. Rolling 14 on 2d6+2 means something different from rolling 14 on 4d8, and the range tells you which end of the distribution you landed on.

• d4, d6, d8, d10, d12, d20 and d100
• Up to twelve dice in one roll
• A modifier added to the total
• Cryptographic randomness with rejection sampling, so no face is favoured
• Six-sided dice drawn as real pip faces
• The arithmetic shown, not just the total
• The possible range and average for the dice you chose
• A history of this session's rolls

The dice roller is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

• Playing a tabletop game without finding the dice
• Rolling a d20 with a modifier for a skill check
• Settling something with a single die
• Generating random numbers in a small range
• Demonstrating probability with repeated rolls