RPG Dice Roller Simulator
Roll any combination of polyhedral RPG dice for Dungeons & Dragons, Pathfinder, or board games. Cryptographically random, zero weighted bias.
Probability Distributions in Tabletop Gaming
The Flat D20 vs Bell Curve (3d6)
A single 20-sided die produces a uniform distribution where every outcome (1 to 20) has an equal 5.0% probability. Rolling multiple dice (like 3d6 or 8d6 fireball) produces a Gaussian bell curve where central values occur far more frequently.
Math of Advantage & Disadvantage
Rolling 2d20 and taking the higher result shifts the expected average roll from 10.5 up to 13.82 (roughly a +3.32 bonus). Furthermore, the chance of rolling a Natural 20 jumps from 5% to 9.75%, while critical failure drops to 0.25%.
Standard Dice Notation (NdX + M)
Standardised in early D&D rulebooks: N represents the number of dice, d indicates die, X defines the number of faces, and + M adds a static ability modifier (e.g., 2d6 + 3 for a greatsword swing).