Free, no signup, works offline

Roll anything.

Polyhedral dice for tabletop games, with the actual probability behind every roll. Pick a die, set a count, add a modifier.

Total

Tap to roll, or press R.

How many

Sides

Modifier

The shape of 1d20

This chart follows the roller above. One die is flat, every face as likely as the next. Put 3 in How many and watch it turn into a curve, because there are far more ways to make a middling total than an extreme one.

Lowest: 1
Highest: 20
Average: 10.50
Each face: 5.00%
Odds: 1 in 20

Every bar the same height. That flatness is the whole point of a single die: 5.00% per face, no favourites.

Pick a die

Each page has the roller plus exact odds for that die.

d41 to 4, average 2.5 d61 to 6, average 3.5 d81 to 8, average 4.5 d101 to 10, average 5.5 d121 to 12, average 6.5 d201 to 20, average 10.5 d1001 to 100, average 50.5

Or a combination

Every one shows the full distribution, not just the average.

2d62–12, avg 7.0 3d63–18, avg 10.5 4d6 drop lowest3–18, avg 12.2 4d64–24, avg 14.0 5d65–30, avg 17.5 6d66–36, avg 21.0 8d68–48, avg 28.0 10d610–60, avg 35.0 2d82–16, avg 9.0 3d83–24, avg 13.5 4d84–32, avg 18.0 2d102–20, avg 11.0 3d103–30, avg 16.5 2d122–24, avg 13.0 3d123–36, avg 19.5 2d202–40, avg 21.0

Tools

The odds, the stat roller, and the comparisons people argue about.

Probability calculatorExact odds for any notation Dice roller for D&DAttacks, damage, saves, advantage Stat rollerSix scores, ranked against every array How to roll stats3d6, 4d6 drop lowest, point buy compared AnyDice alternativeThe same curves without the scripting

Every die, side by side

What each one averages on its own, and what a pair of them does to the shape. The pair column is the interesting one: two dice always cluster.

Die	Range	Average	Each face	Pair range	Pair average	Pair peak
d4	1–4	2.5	25.0%	2–8	5.0	25.0%
d6	1–6	3.5	16.7%	2–12	7.0	16.7%
d8	1–8	4.5	12.5%	2–16	9.0	12.5%
d10	1–10	5.5	10.0%	2–20	11.0	10.0%
d12	1–12	6.5	8.33%	2–24	13.0	8.3%
d20	1–20	10.5	5.00%	2–40	21.0	5.0%
d100	1–100	50.5	1.00%	2–200	101.0	1.0%

Reading across a row shows the trade every dice system is built on. A single die is flat, so every result is equally likely and the roll is maximally unpredictable. Two of the same die cover roughly double the ground but concentrate their results in the middle, so the peak total is several times more likely than either end. Nothing about the individual dice has changed; only how they are combined.

Why the charts

Most dice tools give you a number and stop. The number is the easy part. What actually helps at the table is knowing that 3d6 hits 10 or 11 about a quarter of the time and reaches 18 once in 216 rolls, so you can judge whether a roll was unlucky or just ordinary. Every distribution here is computed by enumerating the whole outcome space, so the percentages are exact rather than sampled.

It also settles the arguments. Whether a greatsword beats a greataxe, whether rolled ability scores really are better than the standard array, whether advantage is worth about three points or about five: these all have exact answers, and none of them are obvious from the averages alone. The odds calculator will take any notation you can write down, and the stat rolling guide works through the character generation case in full.

About this site

DiceCurv is an independent tool, free to use, with no account. Rolls come from your browser's cryptographic random number generator with rejection sampling, so the faces really are flat, and nothing you roll is sent anywhere. More about how it works, or get in touch if a number here looks wrong.