D20 dice roller

The 20-sided die, ready for your next check

This page opens the dice roller set to a 20-sided die, the d20. Click "Roll the dice", click the die or press the space bar: a number from 1 to 20 appears. The roll comes from your browser's cryptographic random number generator, every side has the same chance, and nothing is sent.

You can roll up to 20 dice at once with their total, change the "Number of sides" or use the "Quick picks". "Latest rolls" keeps track of your last 12 results, handy when someone disputes a roll.

What is a d20 used for?

The d20 is an icosahedron: twenty triangular faces, the largest of the Platonic solids. It is the core die of many tabletop role-playing games. To find out whether an action succeeds, you roll it and compare the result to a target number: the check succeeds if the die reaches it. Many tables also count a natural 20 as a critical success and a 1 as a critical failure. It also works for picking one entry from a list of 20 ideas, challenges or events.

The odds with a d20

Each side has a 1 in 20 chance, or 5%: a critical success and a critical failure each happen once in twenty rolls. The average is (1 + 20) ÷ 2 = 10.5. Every extra point on the target takes away 5%.

Frequently asked questions

How do I roll with advantage or disadvantage?

The tool does not do it for you: put 2 in "Number of dice", roll, then keep the higher die (advantage) or the lower one (disadvantage). With advantage, the chance of at least one 20 rises to 1 − (19/20)² = 9.75%, and the chance of reaching 11 or higher to 75%.

What about bonuses like +5?

They are not handled: add them to the die result in your head.