Modifier
+0
History
About this tool
Dice Roller
Dice Roller rolls d4, d6, d8, d10, d12, d20 and d100 with modifiers, keeping a history of your rolls.
How to use it
- Choose a die type and how many to roll.
- Add a modifier if you need one.
- Roll, and read the result and the running history.
Why one die and several dice behave differently
A single die is uniform: every face is equally likely, so a d20 is as likely to roll 1 as 20. That flatness is exactly why d20 systems feel swingy, because a skilled character still fails often.
Rolling several dice and summing them is not uniform. Two d6 produce a triangular distribution peaking at 7, which comes up six times more often than 2 or 12. Three or more dice tend toward a bell curve, which is why systems using 3d6 produce far more predictable results than a single d20.
Worked example
Why 7 dominates on 2d6:
- Ways to roll 21 (1+1)
- Ways to roll 76 (1+6, 2+5, 3+4, and reverses)
- Ways to roll 121 (6+6)
Result: Seven is six times more likely than either extreme, which is the whole basis of craps odds.
When it helps
- Playing tabletop RPGs without physical dice.
- Rolling large handfuls quickly.
- Board games with a lost die.
- Generating random numbers in a range with a familiar interface.
Common mistakes
- Expecting past rolls to influence future ones. Dice have no memory, and a run of low rolls does not make a high one due.
- Assuming a d20 system is fair because the die is uniform. Uniform means swingy, not balanced.
- Reading a short history as a pattern. Small samples look streaky even when perfectly random.
