RPG Dice Roller

How to use RPG Dice Roller

1. Choose the dice type and how many to roll.
2. Add a modifier if your system uses one.
3. Roll, and read the individual results and total.
4. Notation is NdS — 2d6 is two six-sided dice — with any modifier after it.
5. Results come from the browser’s cryptographic random source.
6. Works offline once loaded.

Adding dice changes the shape of the outcome

One d20 is flat: every number equally likely, which is why it produces dramatic swings and why critical hits feel like events. Two or more dice cluster toward the middle — 2d6 produces a seven six times as often as a twelve. That is why 3d6 for a character statistic yields mostly average characters, and why systems using multiple dice feel more predictable than d20 systems even at the same average.

Advantage, disadvantage and the numbers behind them

Rolling two d20 and taking the higher shifts the average from 10.5 to about 13.8 — equivalent to roughly a +3 or +4 bonus, but weighted toward the middle of the range where it matters most. Taking the lower does the reverse. It is an elegant mechanic precisely because its effect is largest when the outcome is genuinely uncertain and smallest when the roll was never going to matter.

Physical dice are not perfectly fair

Cheap moulded dice have rounded edges, air bubbles and hollowed pips that bias them measurably; casino dice are machined flat, sharp-edged and transparent for exactly that reason. A d20 balance test — floating it in salt water and flicking it — reveals the heavier side on many sets. Virtual dice have no geometry to be wrong, which makes them fairer and, most players would say, considerably less fun.