Dice Roller & Coin Flipper

Roll 3D animated polyhedral dice (d4, d6, d8, d10, d12, d20, d100) or flip 3D coins with 100% cryptographic fairness. Supports D&D 5e Advantage, Disadvantage, Modifiers, Drop Lowest, and Roll History.

3D Tumbling Dice Physics 3D Double-Sided Coin Toss CSPRNG True Randomness D&D 5e Advantage & Disadvantage Press Spacebar or Click Tray to Roll
Quick 1-Click Roll (Standard RPG Dice): Click to roll instantly
RPG Presets:
Formula: 1d20
20
14
8
12
19
1
TOTAL RESULT
20

Click anywhere on the tray to re-roll

Session Statistics & Roll Log

Live running log of all rolls and coin flips with export capabilities.

Total Rolls 0
Average Value 0
Natural 20s 0
Natural 1s 0
Time Formula / Type Individual Rolls Total Result
No rolls recorded yet. Roll some dice or flip coins above!
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The Mathematics of Polyhedral Dice, Probability Distributions & Cryptographic Fairness

Whether exploring dangerous dungeons in Dungeons & Dragons (D&D 5e), running tactical skirmishes in Warhammer, resolving critical skill checks in Call of Cthulhu, or making a clean 50/50 decision with a coin toss, understanding dice probability is the foundation of tabletop strategy.

Physical dice suffer from manufacturing imperfections, air bubbles, and edge wear that skew weight distributions. This tool uses cryptographically secure pseudo-random number generation (CSPRNG) via the Web Crypto API, guaranteeing that every side of every die has an exact, uniform mathematical probability.

1. Flat vs. Bell Curve Distribution

Rolling a single die (like 1d20) has a flat uniform distribution (each face has exactly a 5% chance). Rolling multiple dice (like 3d6) creates a Gaussian bell curve where middle values (10 and 11) are exponentially more likely than extremes (3 or 18).

2. The Math of Advantage & Disadvantage

In D&D 5e, Advantage (rolling 2d20 and taking the higher) shifts your expected average roll from 10.5 up to 13.825 (equivalent to a passive +3.32 bonus) and boosts your Natural 20 critical chance from 5% to 9.75%!

3. CSPRNG Cryptographic Fairness

Standard JavaScript Math.random() uses pseudo-random algorithms that can have subtle periodic cycles. We utilize window.crypto.getRandomValues, tapping into hardware system entropy for zero bias.

Polyhedral Dice Statistics & Usage Cheat Sheet

Die Type Geometric Shape Min / Max Expected Average Primary Tabletop / D&D Usage
d4Tetrahedron (4 faces)1 – 42.5Dagger damage, Magic Missile, Healing Potion
d6Cube (6 faces)1 – 63.5Shortsword, Fireball, Rogue Sneak Attack, Board games
d8Octahedron (8 faces)1 – 84.5Longsword, Rapier, Cure Wounds, Paladin Divine Smite
d10Pentagonal Trapezohedron1 – 105.5Heavy Crossbow, Eldritch Blast, Fighter Hit Dice
d12Dodecahedron (12 faces)1 – 126.5Greataxe, Barbarian Hit Dice, Witch Bolt
d20Icosahedron (20 faces)1 – 2010.5Attack Rolls, Ability Checks, Saving Throws (Core D20)
d100 / d%Zocchihedron / Percentile1 – 10050.5Call of Cthulhu skill checks, Wild Magic Surge, Loot tables

Frequently Asked Questions

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