You rolled 15

How does dice notation work?

Dice are named with the letter d and the number of sides: d4, d6, d8, d10, d12 and d20. A number in front says how many to roll, and a number after a plus or minus sign is added to the total. The D&D Basic Rules use 3d8 + 5 as their example: roll three eight-sided dice, add them up, then add 5. In this roller, that is 3 dice, d8, modifier 5.

A d100 is usually rolled at the table with two ten-sided percentile dice numbered 0 to 9, one read as tens and one as ones. Pick d100 here and you get a single result from 1 to 100. The dice that make up a standard set, and what each one is for, are covered in what dice you need for D&D. Odd shapes such as the d100 ball live on our dice wall of fame.

What do advantage and disadvantage do?

In D&D, a D20 Test covers ability checks, attack rolls and saving throws. With advantage you roll a second d20 and use the higher roll; with disadvantage you use the lower one. The roller does the same: it rolls your dice twice, keeps the higher or lower total and shows the other roll struck through. With more than one die it compares the totals of the two rolls.

What are the odds of rolling a certain number on a d20?

Each face of a fair d20 comes up 1 time in 20. To hit a target, count the faces at or above the number you need on the die (the target minus your modifier). Advantage and disadvantage change those odds most in the middle of the range. The figures below are exact counts of the 20 single rolls or 400 pairs of rolls, not simulations.

A natural 20 on an attack roll is a critical hit under the Basic Rules, and a natural 1 on an attack roll always misses. The chance of a natural 20 is 5% on one d20, 9.75% with advantage and 0.25% with disadvantage. The rules list typical difficulty classes from 5 (very easy) through 10, 15 and 20 (hard) up to 30 (nearly impossible).

What is the most common roll on 2d6?

Adding dice makes middle totals more likely than the extremes. With two six-sided dice there are 36 equally likely combinations, and six of them add up to 7, so 7 is the most common total. A 2 or a 12 needs one exact combination each.

How likely is an 18 when rolling ability scores?

The Basic Rules offer random ability scores: roll four d6, keep the highest three, and repeat for six scores (the alternative is the standard array of 15, 14, 13, 12, 10 and 8). Counting all 1,296 ways four dice can land gives these exact odds for a single score:

• An 18: 21 of 1,296 ways, about 1.6%.
• 15 or higher: 23.1%. 8 or lower: 10.5%.
• The average score is 12.24, against 10.5 for a plain 3d6 roll.

What is the average roll of each die?

The average of one die is its highest face plus 1, divided by 2. For several dice, add the averages.

Is this dice roller fair?

Rolls use the Web Crypto getRandomValues() function on our server, which MDN describes as a source of cryptographically strong random values. A common shortcut, taking a random number and dividing by the number of sides, slightly favors low faces, so the roller throws away the few values that would cause that bias and draws again. Our automated tests roll every die thousands of times and check that no face comes up more often than chance allows.

Nothing is stored: each result exists only in the page you receive, and result pages are never cached or shown to anyone else. Physical dice are a different question, covered in our guides to dice materials and metal dice. For the table, a dice tray keeps real rolls in one place.