Dice Roller: Roll Any Dice Online (d4, d6, d20, 2d6+3)
Free online dice roller: roll d4, d6, d8, d10, d12, d20 and d100 or type dice notation like 2d6+3, 4d6 drop lowest or d20 with advantage, see every roll, totals, the exact probability of each total and a chart of your rolls.
Pick lottery numbers for fun
Every combination is exactly as likely as any other, so no picker (this one included) can improve your chances. These are just quick picks in each game's format.
How to write dice
2d6 | two six-sided dice, added |
|---|---|
d20+5, 3d8-2 | add or take away a fixed number |
d6+d8 | mix different dice |
4d6kh3 or 4d6 drop lowest | roll 4, keep the highest 3 (kl keeps the lowest, dh / dl drop) |
d20 adv / d20 dis | roll two d20s, keep the higher / lower |
3d6! | exploding: a die that shows its top number is rolled again and added |
d% | percentile die, 1 to 100 |
4dF | Fudge / Fate dice: each shows -1, 0 or +1 |
The odds for 2d6
Every total as a table
Heads so far this session
The line wobbles a lot at first and settles towards 50% the more you flip: that is the law of large numbers. A long streak is normal: in 100 flips the longest run of heads or tails is usually 6 or 7.
Your list stays in this browser only; it is never put in a link or uploaded.
How the fairness test works
The chi-square goodness-of-fit test compares how often each side came up with how often a fair one would show it on average. It adds up (observed - expected)2 / expected over every side. The p-value is the chance that a perfectly fair die (or coin) would look at least this uneven just by luck. A small p-value (under 0.05, and especially under 0.01) is a sign something is off; a large one means the results are what fair dice normally produce. It can never prove a die is fair, only fail to find a problem, and it needs enough rolls: each side should be expected at least 5 times.
Recent results
History is kept in this browser (it remembers counts, not every roll) until you clear it.
Reproducible (seeded) mode
Normally every result comes from your browser's secure random generator (crypto.getRandomValues) and can't be predicted or repeated. With a seed, the same seed always gives the same sequence of results from the moment the page loads, which is handy for classes, puzzles or checking someone's draw. Seeded results are not secure: anyone with the seed can repeat them.
Online dice roller with the exact odds
Tap a die (d4, d6, d8, d10, d12, d20 or d100) to add it, tap it again for more of the same, or type any dice in standard notation and press Roll (or Enter). Every die is drawn, kept and dropped dice are marked, and the total is shown. Under the roll you get the exact chance of every possible total, a chart with your roll highlighted, and a box that answers "what is the chance of rolling 15 or more?".
Dice notation
NdS means roll N dice with S sides and add them: 2d6 is two ordinary dice. Add or take away a number with d20+5, mix dice with 2d8+1d6. 4d6kh3 (or 4d6 drop lowest) rolls four dice and keeps the highest three, the classic way to roll a role-playing character's ability score. d20 adv and d20 dis roll two d20s and keep the higher or lower, as in Dungeons & Dragons 5th edition. 3d6! explodes: whenever a die shows its top number it is rolled again and added. d% is a percentile die from 1 to 100 and 4dF rolls Fudge / Fate dice, which show -1, 0 or +1.
How the odds are worked out
For plain dice the page combines the chances of each die exactly (a convolution: for two dice it lists every pair of faces). For keep-highest and keep-lowest rolls it walks through every combination of faces and counts how often each total appears, so 4d6kh3 averages exactly 12.2446 and a d20 with advantage shows a 20 39 times in 400. Exploding dice can in theory roll forever, so chances below one in a trillion are left out. When a roll has too many combinations to count (say 60 d20s keeping 30), the page simulates a large number of rolls instead and says so.
Questions
- Are these dice fair?
- Yes. Each face comes from your browser's secure random generator with rejection sampling, so every face has exactly the same chance. You can check it yourself: the Statistics tab keeps a count of every face rolled and runs a chi-square test.
- Can I test my own physical dice?
- Yes. Roll your die many times (at least 30 for a d6, more is better), then in Statistics choose "Test my own die" and type how many times each face came up. The p-value tells you how often a perfectly fair die would look that uneven.
- What does 2d6 most often roll?
- 7, with a chance of 6 in 36 (16.7%), because six pairs add up to 7 and only one pair makes 2 or 12.
- How much does advantage help?
- A d20 averages 10.5; with advantage it averages 13.825, roughly like adding 3 to 5 near the middle of the range.
- Is anything uploaded?
- No. Rolls, odds and history are all worked out in your browser.
Related: Random Number Generator · Statistics Calculator