Roll dice online
Pick how many dice to roll (1 to 6), hit the button, and watch them land: automatic totals and a roll history always at hand.
Roll history (most recent first):
Virtual dice for when the real ones go missing
Dice always disappear at the worst possible moment: halfway through a game of Monopoly, in the middle of a tabletop RPG session, or right when you need to decide who goes first. This roller stands in for up to six 6-sided dice and instantly shows the total, the number that matters in most board games. The roll history keeps track of previous turns, handy for settling disputes without an argument.
Are the rolls truly random?
Every face comes up with the same 1-in-6 probability, thanks to the browser's random number generator. A fun detail: with two dice, the most likely total is 7 (it appears in 6 of the 36 possible combinations, almost 17% of rolls), while 2 and 12 each show up only once in 36. That's why 7 plays a special role in so many games.
Why with two dice a 7 comes up six times more than a 2
With a single die every face is equally likely; with two, what counts is not the faces but the combinations. A 2 can be made one way only (1 and 1), a 7 in six ways (1-6, 2-5, 3-4 and their reverses): six times more likely. The distribution of sums is not flat, it is a pyramid with its peak on seven.
It is the reason why in Monopoly the squares six or seven steps from a crowded position are the most visited, and why in Risk the attacker rolling three dice has an advantage that counting faces does not reveal. Anyone who has played knows it from experience; the arithmetic says why.
Dice have no memory, and games do
After three ones in a row the feeling that «a high one is due now» is almost irresistible, and it is the gambler's fallacy: the die remembers nothing and always restarts at one sixth per face. Unlucky runs exist and are normal: in a hundred rolls, a sequence of three or four identical results in a row is almost certain.
What is true, instead, is that physical dice can be unbalanced: cheap injection-moulded ones have number pips of differing depth, and the six face, with more material removed, is slightly lighter. In casinos the pips are painted flush precisely for this reason, and the dice are changed often.
The dice of role-playing games, and why there are so many
A d20 gives a flat distribution: every result is equally likely, and rolls are unpredictable in the purest sense. A 3d6, that is three six-sided dice added together, gives a similar average range but with a bell curve: the middle values come up far more often and the extremes almost never.
It is a design choice, not a detail: with a d20 surprises are frequent and a weak character can succeed at something hard; with 3d6 the result tends towards the character's real competence and dramatic swings are rare. Changing the type of die changes the character of a game more than almost any other rule.
Advantage, and what it is really worth
Rolling two dice and keeping the better one — what modern games call advantage — does not add a fixed bonus: it shifts the distribution. On a d20 it is worth on average about three and a half points, but the value changes with the difficulty: on middling checks the effect is greatest, on very easy or impossible ones it is almost nil.
It is why advantage feels so strong in play despite being a modest number: it acts exactly where the game is decided. And it works the same way in reverse: keeping the worse die penalises most in uncertain situations, which are the ones players notice.
Nearby tools
For a draw among options there is Wheel of fortune, for numbers Random number generator and for a binary choice Heads or tails. To keep score during the game Scoreboard.