Roll a d20
The one that decides whether you hit. 5% per face.
Roll a d20 to see the result.
Natural 20s and natural 1s
The d20 drives almost every check in modern roleplaying: attack rolls, saving throws, skill checks. A natural 20 is a critical success and a natural 1 a critical failure, each at exactly 5% on every single roll. Streaks feel meaningful and are not - three 20s in a row happens roughly once in every 8,000 sets of three rolls, which across a long campaign is unremarkable.
The odds
Each of the 20 faces has a flat 5.00% chance on every roll, and every roll is independent of the last. There is no "due" number - a face that has not come up in twenty rolls is exactly as likely on the twenty-first as it was on the first.
Fair, and checkable
Every roll is drawn from your browser's cryptographic random number generator using rejection sampling, so no face is even slightly favoured - which is more than can be said for most physical dice. Each roll also produces a receipt anyone can use to reproduce it. How that works.
To roll a different combination, or to add a modifier, the main dice roller takes any number of dice with any number of sides.
Other dice
- Roll a d4The four-sided die. Smallest of the standard polyhedral set.
- Roll a d6The ordinary cube. Every board game in the cupboard uses one.
- Roll a d8Eight faces, 12.5% each. Common for medium weapon damage.
- Roll a d10Ten faces. Used alone, or in pairs to make percentages.
- Roll a d12Twelve faces. The most under-used die in the set.
- Roll a d100Percentile. One number in a hundred, flat odds throughout.
- Roll 2d6Two ordinary dice, totalled. The shape of most board games.
- Roll 3d6Three dice, totalled. The classic ability-score roll.
- Roll 2d10Two ten-sided dice, totalled. Range of 2 to 20 on a curve.