About the Dice Roller
What is a dice roller?
A dice roller is a tool that rolls virtual dice and shows each die and the total.
This dice roller draws every die with the Web Crypto API's crypto.getRandomValues() and rejection sampling, so each face of a d6 comes up 1 time in 6. It rolls up to 100 virtual dice at once, from a two-sided die to a d1000, and works out the exact odds of every total. The only exception is a very large keep roll, such as 24d100kh23.
What should you know before you roll dice online?
- Every face has the same chance. A d6 lands on each number 16.67% of the time, and a d20 lands on each number 5% of the time.
- Totals are not equally likely. Two dice make 7 in 6 of their 36 combinations, more than any other total.
- Advantage changes the odds a lot. Rolling two d20s and keeping the higher raises the average from 10.5 to 13.825 and the chance of a 20 from 5% to 9.75%.
- Every roll is independent. A run of low numbers says nothing about the next roll.
How do you roll dice online?
- Pick a die. Choose d4, d6, d8, d10, d12, d20 or d100, or type notation such as 2d6+3.
- Set the number of dice and the modifier. The notation box updates as you change them.
- Roll. Press Roll the dice, press Space, or click the dice.
- Read the result. The dice land first, then the total and its chance appear, and Recent rolls keeps the last 20.
Example
The notation 2d6+3 will be converted to two dice, a total and the odds of that total:
2d6+3: (4 + 2) + 3 = 9
Range: 5 to 15, average 10
Chance of this total: 13.89%
This total or more: 72.22%
With 4d6kh3 the dice roller throws four dice and drops the lowest, so 6, 2, 5 and 3 give 6 + 5 + 3 = 14, a total that comes up 12.35% of the time.
What does dice notation like 2d6+3 mean?
Dice notation writes a roll as the number of dice, the letter d and the number of sides.
So 2d6+3 means roll two six-sided dice and add 3, and d20 means one twenty-sided die. The dice roller also reads kh and kl, which keep the highest or lowest dice, and d%, a percentile die from 1 to 100.
Common dice notation with the range and average of each roll
| Notation | Meaning | Range | Average |
|---|
d20 | One twenty-sided die | 1 to 20 | 10.5 |
2d6 | Two six-sided dice added together | 2 to 12 | 7 |
2d6+3 | Two six-sided dice plus 3 | 5 to 15 | 10 |
3d6 | Three six-sided dice | 3 to 18 | 10.5 |
4d6kh3 | Four six-sided dice, keep the highest 3 | 3 to 18 | 12.24 |
2d20kh1 | Two d20s, keep the higher (advantage) | 1 to 20 | 13.83 |
2d20kl1 | Two d20s, keep the lower (disadvantage) | 1 to 20 | 7.18 |
d% | One percentile die | 1 to 100 | 50.5 |
What are the odds for each total with two dice?
With two six-sided dice, 7 is the most likely total and 2 and 12 are the least likely.
Chance of each total when rolling two six-sided dice (2d6), out of 36 combinations
| Total | Ways out of 36 | Chance |
|---|
| 2 | 1 | 2.78% |
| 3 | 2 | 5.56% |
| 4 | 3 | 8.33% |
| 5 | 4 | 11.11% |
| 6 | 5 | 13.89% |
| 7 | 6 | 16.67% |
| 8 | 5 | 13.89% |
| 9 | 4 | 11.11% |
| 10 | 3 | 8.33% |
| 11 | 2 | 5.56% |
| 12 | 1 | 2.78% |
For any roll with up to 150 possible totals, type it into the dice roller and the chart under the result shows the chance of each one.
What is the difference between an online dice roller and physical dice?
An online dice roller picks each face with a random number generator. Physical dice depend on the throw and on the die itself.
Online dice roller compared with physical dice
| Option | How the number is chosen | Trade-offs | Best for |
|---|
| Online dice roller | A random number generator picks each face | Equal odds by design and dice from 2 to 1,000 sides, but you trust the code and lose the feel of the throw | Many dice, unusual dice, remote games, knowing the odds |
| Physical dice | The throw, the surface and the die's balance decide | Everyone at the table sees the roll, but you need the right dice and a fair throw | Board games and tabletop sessions in person |
Common mistakes
These dice roller mistakes change the result without anyone noticing.
- Adding the modifier to every die. 2d6+3 adds 3 once, to the total. If each die gets +3, write 2d6+6.
- Typing a space instead of a plus. 2d6 3 is ambiguous, so the dice roller asks for + or - between groups instead of guessing.
- Rerolling until the number looks right. Each roll is independent, so a reroll only replaces the result. Agree on the roll before you make it.
Common Use Cases
People use a dice roller when the dice are missing or the roll needs unusual dice.
- Board games. Roll a dice or two for any game that uses six-sided dice.
- Tabletop role-playing games. d20 checks with advantage, damage like 2d6+3, and ability scores with 4d6kh3.
- Classrooms. Probability lessons with the odds chart and hundreds of rolls.
- Random numbers. The Percentile roll gives a number from 1 to 100.
For a two-way choice, the Coin Flip gives heads or tails. Spin the Wheel picks from a list of names, and the Random Number and String Generator makes numbers in any range.
Frequently Asked Questions
How does an online dice roller work?
An online dice roller picks a random number for each die and adds them up. This one uses crypto.getRandomValues(), the browser's cryptographic random number generator, with rejection sampling so every face is equally likely.
What are the odds of rolling a 7 with two dice?
The odds of rolling a 7 with two dice are 6 in 36, or 16.67%. It is the most likely total, because six pairs make 7, from 1 and 6 to 6 and 1.
What does advantage mean on a d20 roll?
Advantage means you roll two d20s and keep the higher one. It raises the chance of a 20 from 5% to 9.75%, and the dice roller writes it as 2d20kh1.
Are online dice rolls fair?
Online dice rolls are fair when every face has the same chance. This dice roller draws each face with crypto.getRandomValues() and rejection sampling, so no face comes up more often than another.
How many dice can you roll at once?
The dice roller rolls up to 100 dice at once, each with 2 to 1,000 sides. Mixed rolls like 1d8+1d6+2 count toward the same limit.
Can you roll dice on your phone?
Yes, the dice roller works in a phone browser with no app to install. Tap Roll the dice or the dice themselves, and the total appears when the dice land.