Dice Roller (D4–D20)

Purpose

Roll polyhedral dice quickly for D&D, TRPGs, board games, classroom tasks, and small random decisions.

How to use

1. Choose the number of dice.
2. Select D4, D6, D8, D12, or D20.
3. Roll the dice.
4. Check the total and individual values.

One die and several dice behave differently

A single six-sided die gives each face about 16.7 percent, a perfectly flat distribution. Sum two dice and that changes. Seven can be made six different ways while two can be made only one, a six-fold difference in probability.

So totals cluster near the middle and thin out at the extremes, and the effect strengthens with every die you add. Use fewer dice when you want luck to dominate and more when you want stable results.

Choosing a face count

A D20 gives exactly five percent per face, which makes probability arithmetic clean. Raising the target by one lowers the success rate by precisely five percentage points, which is why it dominates as a check die.

A D12 is tidy because twelve divides by two, three, four, and six, so results group cleanly. It also works for choosing among twelve options or picking a clock direction. D4 and D8 fill the gap between D6 and D20.

Totals and individual results together

Rolling several dice shows the total and each die separately, so rules that care about individual values work directly. An advantage roll, where you take the higher of two, is handled as-is.

Up to six dice roll at once. For more than that, roll in batches, or use the number picker with an explicit range when you need something much wider.

Short runs look lopsided, and that is fine

Rolling three sixes in ten attempts does not mean anything is broken. Getting a specific face three or more times in ten rolls happens about twenty-two percent of the time, and approaching the theoretical distribution takes hundreds of rolls.

Each roll is fully independent, so a bad streak gives no reason to expect a good one next. Most moments where a game feels unlucky are exactly this short-run variance.

Less biased than a physical die

A moulded die can carry a slightly offset centre of mass, and edges wear down with use. A computed result has no physical bias at all.

The rolls also stay visible on screen, which removes arguments when a rule depends on the exact result. Full screen mode makes it large enough for a group to read together.

Examples

• D&D and TRPG rolls
• Roll a D20 for a skill check
• Board game helper
• Quick tie breaker

Notes

• The result is generated in the browser.
• For formal gambling or regulated games, use approved systems instead.

FAQ

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