The D20 (twenty-sided die) is the most iconic die in tabletop role-playing games, particularly Dungeons & Dragons. This virtual dice roller simulates rolling a D20, generating a random number between 1 and 20.
How To Use The D20 Roller
- Set the number of times you want to roll
- Set how many D20 dice to roll per attempt
- Click "Roll dice" to generate your results
- View individual roll results or the grand total
Common Uses For D20 Dice
- Attack rolls: Determine if attacks hit their target
- Saving throws: Resist spells, traps, and other effects
- Ability checks: Test skills like Perception, Stealth, or Persuasion
- Initiative: Determine combat order
D20 Probability
Each face of a fair D20 has an equal 5% chance of landing face up:
| Result | Probability |
|---|
| 1-20 | 5% each |
The expected average roll is 10.5 when rolling a single D20.
Critical Rolls
In most d20 systems:
- Natural 20: A critical success, often dealing double damage on attacks
- Natural 1: A critical failure, automatically missing regardless of bonuses
The D20 System
The d20 forms the foundation of many popular RPG systems:
- Dungeons & Dragons (3rd, 4th, and 5th editions)
- Pathfinder (1st and 2nd editions)
- Starfinder
- d20 Modern
- Many Open Gaming License (OGL) games