Question 1

What is a D20 die?

Accepted Answer

A D20 (twenty-sided die) is a polyhedral die in the shape of a regular icosahedron with 20 equilateral triangular faces, each numbered from 1 to 20. It is the most commonly used die in tabletop role-playing games like Dungeons & Dragons (D&D), Pathfinder, and many other RPG systems. Each face has an equal 5% (1/20) probability of being rolled.

Question 2

How many sides does a D20 have?

Accepted Answer

A D20 has exactly 20 sides (faces). Each side is an equilateral triangle, and together they form a regular icosahedron — one of the five Platonic solids. The 20 faces are numbered 1 through 20, with each number appearing exactly once.

Question 3

What is the probability of rolling a 20 on a D20?

Accepted Answer

The probability of rolling any specific number on a fair D20, including a natural 20, is exactly 1 in 20, or 5% (0.05). This means that on average, you'll roll a natural 20 once every 20 rolls.

Question 4

What is a natural 20 in D&D?

Accepted Answer

A 'natural 20' (often abbreviated as 'Nat 20') in Dungeons & Dragons means the D20 shows 20 before any modifiers are added. On attack rolls, a natural 20 is always a critical hit, regardless of the target's Armor Class. Critical hits allow you to roll all damage dice twice in D&D 5e.

Question 5

What is a natural 1 (critical fail) in D&D?

Accepted Answer

A natural 1 on a D20 attack roll in D&D 5e means the attack automatically misses, regardless of any modifiers or the target's Armor Class. On death saving throws, rolling a natural 1 counts as two failures instead of one.

Question 6

Is this online D20 roller truly random and fair?

Accepted Answer

Yes, our online D20 dice roller uses the Web Crypto API's cryptographically secure random number generator (CSPRNG), the same technology used in banking and encryption. This ensures a perfect 5% probability for each of the 20 possible outcomes on every single roll.

Question 7

Can I use this D20 roller for Dungeons & Dragons?

Accepted Answer

Absolutely! Our free online D20 roller is perfect for Dungeons & Dragons (all editions including 5e), Pathfinder (1e and 2e), Call of Cthulhu, Starfinder, and any other tabletop RPG that uses D20 rolls.

Question 8

What is the average roll on a D20?

Accepted Answer

The mathematical average (expected value) of a fair D20 roll is 10.5. This is calculated by adding all possible outcomes (1+2+3+...+20 = 210) and dividing by the number of faces (210 ÷ 20 = 10.5).

Question 9

What is advantage and disadvantage in D&D 5e?

Accepted Answer

When you have advantage, you roll two D20s and use the higher result. When you have disadvantage, you roll two D20s and use the lower result. Advantage effectively raises your average roll from 10.5 to approximately 13.82, while disadvantage lowers it to about 7.18.

Question 10

What are all the dice in a standard D&D dice set?

Accepted Answer

A standard D&D polyhedral dice set includes seven dice: D4, D6, D8, D10, D% (percentile), D12, and D20. The D20 is the most frequently rolled die in most RPG systems.

D20 Dice Roller