Dice Roller

Roll any number of four, six, eight, ten, twelve, twenty or hundred-sided dice, add a modifier if your game uses one, and see each die plus the total. It's for tabletop games, board games with lost dice, and anyone who wants a quick random number.

How to use it

1. Choose how many dice.
2. Pick the number of sides.
3. Add a modifier if you need one.
4. Press Roll the dice.

When it helps

• Tabletop role-playing sessions.
• Board games with missing dice.
• Making a random choice.
• Teaching probability.

Good to know

• Notation like 2d6+3 means two six-sided dice plus 3.
• Use the d100 for percentage rolls.
• Each roll is independent; streaks don't mean anything.

How the dice are rolled

Each die uses your browser's cryptographic random number generator, the same source used to create encryption keys. A six-sided roll picks a number from 1 to 6 with equal chance, using a method that avoids the small bias you get from naively taking a remainder. Every die in a roll is independent of the others.

The total shown adds all the dice and then your modifier, and the line below lists each individual result, so you can see whether you rolled, say, a 6 and a 1 or two 4s.

Worked example: a tabletop attack

A fighter swings a sword for 2d6+3 damage. Choose 2 dice, six sides, and a modifier of 3. A result of 4 and 5 gives a total of 12, shown with the note that the dice summed to 9. The odds are worth knowing: two six-sided dice total 7 more often than any other number, about one time in six.

For an ability check, roll a single d20 and add your bonus. On a d20 every number from 1 to 20 is equally likely, so a natural 20 comes up five percent of the time.

Dice sizes and what they're used for

The d6 is the classic board game die. Role-playing games add d4 for small damage, d8 and d10 for weapons and spells, d12 for big weapons, d20 for checks and attacks, and d100 for percentages. Rolling a d100 gives a number from 1 to 100, equivalent to two ten-sided dice read as tens and units.

If a game calls for a mix of dice, roll each type separately and add the totals yourself. The tool keeps things simple by rolling one type at a time.

Probability notes for the curious

With one d6, every face has a one in six chance. With two d6 the totals aren't equally likely: there's one way to roll a 2 and six ways to roll a 7, so 7 comes up six times as often as 2 or 12. Three dice produce an even rounder bell curve, with totals near 10 and 11 most common.

This is why games using several dice feel more predictable than single-die games. If you want wild swings, use one big die like a d20. If you want steady outcomes, roll several smaller ones.

Questions