Dice roller
Standard dice notation — 4d6+2, advantage, disadvantage and roll history.
Count, d, sides, optional kh/kl to keep highest or lowest, optional modifier
How it works
Dice notation is the standard shorthand from tabletop gaming: a count, the letter d, and the number of sides.
d20- One twenty-sided die.
3d6- Three six-sided dice, summed.
2d8+4- Two eight-sided dice plus a flat modifier.
4d6kh3- Roll four, keep the highest three — the classic D&D ability-score method.
2d20kh1- Advantage: roll two d20s, take the better.
2d20kl1- Disadvantage: roll two, take the worse.
What advantage is actually worth
Rolling two d20s and keeping the higher raises the average from 10.5 to 13.825 — worth about +3.3 on average, but the effect is not uniform. It helps most when you need a middling roll (around +5 at a target of 11) and least at the extremes, where you were nearly certain either way. That non-linearity is why advantage feels better than a flat bonus in tight situations.
Why 4d6 drop lowest
3d6 averages 10.5 with a symmetric spread. 4d6 keeping the best three averages about 12.24 and skews high, producing characters that are above average without guaranteeing it. It is a deliberate design choice about the shape of the distribution, not just the mean.
Fairness
Every die uses crypto.getRandomValues with an unbiased range mapping. There is no
“due for a six” — each roll is independent of everything before it.