D20 Dice Roller

Roll a 20 sided die

This d20 dice roller rolls one 20 sided die each time you press Roll and shows the result in big type. Natural 20s and natural 1s get a call-out, and every roll goes into a history list. It suits a quick check in a tabletop game, a random pick from 20 options, or a classroom game where the whole room should see the number.

How to use the d20 dice roller

1. Press Roll. The page also makes one roll when it loads, so a number is already waiting.
2. Watch the die tumble for a moment and settle on a number from 1 to 20.
3. Look under the total for a note. A 20 says “Natural 20” and a 1 says “Natural 1”.
4. Press the space bar for the next roll.

How a d20 behaves

Every face is 5 percent

A d20 is flat. Rolling a 10 is exactly as likely as a 20 or a 1: each has a 1 in 20 chance. Two six sided dice are different, because their middle totals come up far more often than the ends. That flat spread is why many games use a d20 for checks where any result should be possible. Each point of bonus usually moves your chance of success by 5 percent.

Natural 20s and natural 1s

In many tabletop role-playing games, a natural 20 is the best roll possible, often an automatic hit or a critical success. A natural 1 is often an automatic miss. The roller marks both so nobody argues about whether a 20 was rolled or reached with a bonus. Each one turns up about once in every twenty rolls.

Rolling several at once

Set Number of dice above 1 if you want two or more d20s side by side. Any 20 or 1 is highlighted, and the total is the sum. The natural note only appears for a single die.

Ways to use a d20

• Checks and saving throws. Roll, then add your bonus in your head. For the bonus and advantage built in, switch to the tabletop RPG dice roller.
• Random tables. Many game books and homemade lists have 20 entries for weather, names or events. Roll and read the matching line.
• Classroom turns. Number 20 questions or 20 students and roll to see who goes next. A repeat just means roll again.
• Number practice. Younger students can roll and read the number aloud, or roll twice and add the results.
• Low or high. Agree that 1 to 10 means one option and 11 to 20 means the other. For a plain 50/50, a coin flip is quicker.

Fair rolls

Each roll uses your browser’s cryptographic random generator (crypto.getRandomValues). No face is favored, and no roll depends on the one before it. A run of low numbers is ordinary chance, not a cold die, and there is no point blowing on it.

The history logs every roll as notation, such as “1d20: 17”, newest first. It clears when you leave the page, while your dice settings stay saved in this browser.