Dice Roller

This dice roller replaces physical dice for board games, tabletop RPGs and classroom probability. Choose the type (d4, d6, d8, d10, d12, d20 or d100) and how many to roll, add a modifier, and press Roll to see each die and the total.

For Dungeons & Dragons, a d20 roll can use advantage (roll two, keep the higher) or disadvantage (keep the lower). Every roll uses your browser's cryptographic random number generator with unbiased sampling, and the last 30 rolls are kept in a history.

How to use it

1. Choose the dice type (d4 to d100).
2. Set how many dice to roll and an optional modifier.
3. For a d20, choose normal, advantage or disadvantage.
4. Press Roll and read each die, the total and the history.

How it is calculated

Each die is an independent, uniformly random integer from 1 to the number of sides, generated with crypto.getRandomValues and rejection sampling so no face is favoured. The total is the sum of the dice plus the modifier.

Worked example

Rolling 2d6 gives a total between 2 and 12, with 7 the most likely result (6 of 36 combinations, about 16.7%). A d20 with +5 ranges from 6 to 25. Rolling with advantage raises the chance of a natural 20 from 5% to 9.75%.

Who uses it

• Board games when the dice go missing
• D&D, Pathfinder and other tabletop RPGs
• Teaching probability in class
• Random decisions and party games

Tips

• Use 3d6 for classic character stats; 4d6 drop-lowest is common in D&D (roll 4 and ignore the lowest).
• The average of one die is (sides + 1) ÷ 2 to 3.5 for a d6 and 10.5 for a d20.
• Rolls are not saved anywhere; screenshot the history if you need proof.

Free, private and instant: every calculation runs in your browser, nothing is uploaded or stored, and there is no sign-up or limit. Related calculators: time calculator, date calculator, scientific calculator.