Roll dice

How to roll the dice

1. Set the Number of dice with − and +, from 1 to 10. It starts at 2.
2. Choose the Sides on each die: 4, 6, 8, 10, 12 or 20, or Other for any number from 2 to 1,000.
3. Press Roll, or click the dice. They tumble for a moment, then show their faces and the total.

Six-sided dice show their pips; the others show their number. Last rolls lists your last 10 rolls, newest first, so you can check what came up a turn ago.

Dice notation: 2d6, d20 and the rest

Games write dice as a short code: the number before the d is how many dice, the number after it how many sides.

• d6 or 1d6: one six-sided die.
• 2d6: two six-sided dice, added together, for a total from 2 to 12.
• d20: one die of 20 sides, the main die of many role-playing games.
• 3d6+2: three six-sided dice, plus 2. Roll 3 dice of 6 sides here and add the 2 yourself.
• d100 or d%: a number from 1 to 100. Choose Other and type 100.

The chances with two dice

One die is even: each face of a six-sided die has a 1 in 6 chance. The total of two dice isn’t. They can land in 36 ways, and more of those ways add up to the middle totals. A 7 comes from 1 and 6, 2 and 5, 3 and 4, and the same pairs the other way round: 6 ways out of 36.

Total	Ways out of 36	Chance
2	1	2.8%
3	2	5.6%
4	3	8.3%
5	4	11.1%
6	5	13.9%
7	6	16.7%
8	5	13.9%
9	4	11.1%
10	3	8.3%
11	2	5.6%
12	1	2.8%

With three dice, totals bunch even more around the middle: 10 and 11 come up 27 times in 216 each, while 3 and 18 come up once each.

Board games and role-playing games

• Board games often use two six-sided dice. Knowing that 7 is the most likely total, and 2 and 12 the least, helps you judge a move or a risk.
• Tabletop role-playing games use a set of six dice: d4, d6, d8, d10, d12 and d20. A d20 usually decides whether an action works, the others how much damage it does. To roll with advantage, roll 2 dice of 20 sides and keep the higher.
• In class: roll two or three dice and have pupils add them up.
• Lost a die? Choose the dice your game needs and play on.

Why a digital roll is fair

A real die is only as fair as its shape and its throw. Worn edges, bubbles in the plastic or uneven pips can make some faces come up a little more often, and a die that’s dropped rather than thrown barely turns.

Here, each die is drawn by your browser’s secure random numbers, the kind used for encryption, with every face exactly as likely. The result is picked before the tumble, which only shows it. Earlier rolls don’t change the next one: after three sixes in a row, a six is still 1 in 6.