The Dice Roller and the Odds Behind Every Roll
Roll 2d6 or 8d10 in a click, and see why 7 shows up six times as often as 12.
Quick answer: A dice roller generates random results for any number and type of dice, from one d6 to 8d10. With two six-sided dice there are 36 possible combinations, so a total of 7 turns up in 6 of them (16.7%) while 12 turns up in only 1 (2.8%). That gap is why 7 feels lucky.
Board games lose dice. Tabletop groups meet over video calls. Somebody always needs a d20 and nobody in the room has one. An online roller fixes the practical problem, and it happens to be a good way to watch probability behave across a few hundred rolls.
Setting up a roll
Three inputs. How many dice, how many sides each, and any modifier added to the total. Standard sets run d4, d6, d8, d10, d12, d20 and d100, and the shorthand works the way it reads: 3d6+2 means roll three six-sided dice, add them together, then add two. A fireball in most fantasy systems is 8d6, which is tedious with real dice and instant here.
Reading the output
A good roller shows each die individually as well as the total. That matters more than it sounds. Systems that let you reroll ones, keep the highest three of four, or count successes above a threshold all need the individual values, not the sum. If you only ever see one number, the roller is not much use beyond a coin flip.
Run your own numbers
It is free, there is no sign-up, and it works on your phone.
Open the Dice RollerWhy 7 shows up so often
Two six-sided dice produce 36 equally likely combinations. Exactly one of them makes 2 (both ones) and one makes 12 (both sixes). Six of them make 7: 1+6, 2+5, 3+4, 4+3, 5+2 and 6+1. So 7 arrives 6 times in 36, or 16.7%, and 12 arrives 2.8% of the time. Roll a hundred times and you would expect roughly 17 sevens and 3 twelves.
The average of two dice is also 7, which is why Catan puts the robber there and why craps is built around it. Nothing mystical, just counting.
A run of sixes is not a broken roller
Four sixes in a row on one d6 has odds of (1/6)4, about 1 in 1,296. Rare in isolation, but roll a few thousand times across an evening and a run like that somewhere is close to expected. The reverse catches people out too: the chance of at least one 6 in four rolls is 1 minus (5/6)4, which comes to 51.8%. Slightly better than a coin flip, not the near-certainty most people assume.
Where a roller beats physical dice
Real dice are not perfectly fair. Cheap ones have air bubbles, chipped corners and rounded edges that quietly favour some faces. A digital roller has none of that, though it has a limit of its own: browser randomness is fine for a game night and not appropriate for anything with money riding on it. A web toy is not where you would generate a password either.
The practical wins are bulk and record keeping. Rolling 8d6 takes one click. So does rolling 100d6 if you want to watch a distribution appear in front of you, which teaches probability faster than any explanation.
Common questions
How do I roll with advantage? Roll 2d20 and take the higher result. It helps more than people expect. If you need 15 or better on a d20, that is 6 outcomes out of 20, or 30%. With advantage you only fail when both dice fail, so your chance of success is 1 - (0.7 × 0.7) = 51%. A long shot becomes a coin flip.
Is an online roller genuinely random? It is pseudorandom, produced by an algorithm rather than by physics. For games the difference does not matter, and nobody can tell across a campaign. For anything where fairness carries legal weight, use a properly licensed generator instead.
What if I need a number in a range rather than dice? Use a random number generator where you set the minimum and maximum. Dice only produce certain shapes of distribution, and picking a raffle winner from 237 entries is a different job.
Can I work out odds for stranger combinations? Yes, although counting by hand gets ugly past two dice. Feed the number of trials and the chance of success into a probability calculator and let it handle the arithmetic.