Dice Roller - Standard Dice & Custom Dice Notation

How to use this tool

1. Choose a die type. In Simple mode, choose a preset d4, d6, d8, d10, d12, d20, or d100, then set the number of dice and an optional modifier. For custom sides, use Dice Notation instead.
2. Or type an expression. Switch to Dice Notation for expressions like `4d6kh3` or `2d20kl1+5`, or for custom-sided dice such as `1d7`. Click an example chip to prefill.
3. Roll. Click Roll (or press Enter in the notation input). Each die result is shown individually; dropped dice appear grayed out.
4. Review history. Your last 20 rolls are listed below the result. Click any expression in the history to re-run it in the notation input.

Simple presets and custom-sided dice

Simple mode offers one-tap presets for the standard polyhedral dice: d4, d6, d8, d10, d12, d20, and d100. Choose a preset, set how many to roll, and add an optional modifier.

For a die with a different number of sides, switch to Dice Notation and enter an expression such as 1d7 or 2d30. Notation accepts custom side counts from d2 to d10,000, so the Simple presets are not the limit on supported dice.

What dice notation is supported

The Notation tab accepts full dice notation. Here are the building blocks:

• 2d6: roll 2 six-sided dice and add the results
• 2d6+3: same, plus a flat modifier of +3
• 4d6kh3: roll 4d6, keep the highest 3 (drop the lowest)
• 2d20kl1: roll 2d20, keep the lowest 1 (disadvantage in D&D 5e)
• 3d8!: exploding dice: re-roll and add whenever the max value is rolled
• 2d6+1d4-2: two dice groups plus a negative modifier

You can combine these freely. 4d6kh3+1d4! is a valid expression. Dice count is capped at 100 per group and 200 total; sides can be 2–10,000.

How randomness works

Every die roll calls crypto.getRandomValues: the browser's cryptographically secure random number generator. It is seeded by your operating system's entropy pool, making it far stronger than Math.random(). Rejection sampling eliminates modulo bias: values that would skew the distribution are discarded and a new value is drawn instead.

Keep-highest and keep-lowest

4d6kh3 is the classic D&D ability score roll: roll four d6s, discard the lowest. kl does the opposite: keep the lowest N. k without a suffix defaults to keep-highest. Dropped dice are shown grayed out with a strikethrough in the result; they don't contribute to the total.

Exploding dice

When a die rolls its maximum value (e.g., 6 on a d6), an exploding die (`!`) is re-rolled and the new value is added to the chain. This continues until a non-max value is rolled, up to 20 explosions per die (a safety cap that is statistically never reached). The full explosion chain is shown below the dice chips for transparency.

Common RPG expressions

• D&D 5e ability score: 4d6kh3
• Advantage: 2d20kh1
• Disadvantage: 2d20kl1
• Fireball (average): 8d6
• Sneak attack (10th level rogue): 5d6
• Savage Worlds trait: 1d8!