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D20 Dice Roller Calculator
Roll 20-sided dice for D&D, RPGs, and tabletop gaming with statistical analysis
D20 Dice Configuration
Choose how many d20 dice to roll simultaneously
Add your ability modifier, proficiency bonus, or other bonuses
Difficulty Class (DC) or Armor Class (AC) to beat - Easy
D20 #1
1
💀 Nat 1!
Roll Results
1
Total Roll
1
With Modifier
0
Natural 20s
1
Natural 1s
Individual Results: 🎲1 = 1
With Modifier: 1 + 0 = 1
Result: ❌ FAILURE (Target: 10)
Average per die: 1.0 / 20 (5.0%)
Success Probability Analysis
55.0%
Success Chance
5%
Critical Hit
5%
Critical Failure
DC 5
80%
Very Easy
DC 10
55%
Easy
DC 15
30%
Medium
DC 20
5%
Hard
D&D Quick Reference
Natural 20
Critical Success
Auto-hit, maximum effect
Natural 1
Critical Failure
Auto-miss, potential complications
Advantage
Roll twice, take higher
+25% average success rate
Disadvantage
Roll twice, take lower
-25% average success rate
D20 Statistics
Each face probability:1/20 (5%)
Expected value:10.5
Standard deviation:5.77
Variance:33.25
Shape:Icosahedron
Difficulty Classes
DC 5Very Easy
DC 10Easy
DC 15Medium
DC 20Hard
DC 25Very Hard
DC 30Nearly Impossible
Understanding D20 Dice in RPGs
What is a D20 Die?
The D20 is a 20-sided polyhedral die shaped like an icosahedron. It's the signature die of Dungeons & Dragons and many other tabletop role-playing games, used for most ability checks, attack rolls, and saving throws.
Physical Properties
- •20 triangular faces numbered 1-20
- •12 vertices and 30 edges
- •Most spherical of all dice shapes
- •Rolls further than other dice types
D&D Roll Mechanics
Basic Roll: 1d20 + modifier vs. target number
Attack Roll: 1d20 + attack bonus vs. AC
Saving Throw: 1d20 + save modifier vs. DC
Special Results
- •Natural 20: Critical success, auto-hit
- •Natural 1: Critical failure, auto-miss
- •Advantage: Roll 2d20, take highest
- •Disadvantage: Roll 2d20, take lowest