Dice roller

This dice roller uses the standard dice notation from tabletop role-playing games like Dungeons and Dragons. Type an expression such as 1d20+5 or 3d6 and get fair random results with each individual die shown, so you can play without physical dice or test probability ideas.

How to use it

1. Enter the dice expression.
2. Roll and read the total and the individual dice values.

Dice notation explained

NdM+K means roll N dice with M sides each and add K.

• 1d20: one twenty-sided die, results 1 to 20.
• 2d6: two six-sided dice added together, results 2 to 12.
• 1d20+5: a d20 plus a modifier of 5, results 6 to 25.
• 3d8-2: three eight-sided dice minus 2.
• 1d100 or d%: percentile roll.

Probability matters

One die gives a flat distribution: each face of a d20 has a 5% chance. Adding dice creates a bell curve. With 2d6, 7 is the most likely total at 6 in 36 (16.7%), while 2 and 12 each have only a 1 in 36 (2.8%) chance. That is why 3d6 for character stats clusters around 10 and 11, while 1d20 is much swingier.

Fairness

Rolls use the browser's cryptographically secure random number generator, so each face is equally likely and results cannot be predicted. Physical dice, especially cheap ones, can be slightly biased by uneven weight or rounded edges.