Quick Roll
Batch Simulation
Roll the same configuration many times to see how results are distributed. Useful for probability analysis and classroom demonstrations.
Roll History
What Is a Dice Roller?
A dice roller is a browser-based tool that generates random results for standard polyhedral dice. The most common types are the D6 (six-sided), D20 (twenty-sided), and D100 (percentile), though this roller supports any die from D2 to D100 as well as custom dice with up to 1,000 sides. Online dice rollers are used for tabletop RPGs, board games, classroom probability lessons, and statistical simulations whenever physical dice are unavailable or inconvenient.
How to Use This Dice Roller
Select from D2 through D100 in the dropdown, or click any Quick Roll button to jump straight to that die. Choose Custom to enter any number of sides from 2 to 1,000.
Use the plus and minus buttons or type a value. You can roll 1 to 100 dice at once. For 2D6, set the type to D6 and the count to 2.
Enter a positive or negative integer to add to the total. Leave it at 0 if no modifier applies. The modifier is always displayed separately so you can see both the raw dice total and the adjusted final total.
Normal keeps all results. Advantage rolls 2D20 and uses the higher. Disadvantage rolls 2D20 and uses the lower. Drop Lowest removes the smallest result from the pool. Drop Highest removes the largest.
Each die result appears on screen individually. Kept dice are highlighted; dropped dice are marked as dropped. The dice total, modifier, and final total are shown clearly below.
Type directly into the notation field: for example, 4d6-2 or 2d20+5. Both lowercase and uppercase D are accepted.
Dice Types and What They Mean
Polyhedral dice are named by their number of faces. A D8 has eight faces numbered 1 through 8. Each face has the same probability of landing face-up on a fair die.
| Die | Sides | Possible Results | Probability Per Face | Common Use |
|---|---|---|---|---|
| D2 | 2 | 1 to 2 | 50% | Coin-flip equivalent |
| D4 | 4 | 1 to 4 | 25% | Weapon damage in RPGs |
| D6 | 6 | 1 to 6 | 16.67% | Board games, RPG damage |
| D8 | 8 | 1 to 8 | 12.5% | RPG weapon damage |
| D10 | 10 | 1 to 10 | 10% | Percentile rolls (with another D10) |
| D12 | 12 | 1 to 12 | 8.33% | Heavy weapon damage in RPGs |
| D20 | 20 | 1 to 20 | 5% | Attack rolls, saving throws |
| D100 | 100 | 1 to 100 | 1% | Percentile rolls and tables |
What Does 2D6 Mean?
The notation 2D6 means roll two six-sided dice and add the results together. The total ranges from 2 (both dice show 1) to 12 (both dice show 6). More generally:
3d8 = three eight-sided dice, total from 3 to 24.4d6+3 = four six-sided dice, sum plus 3, total from 7 to 27.
This notation is universally recognized in tabletop gaming. The lowercase or uppercase d is interchangeable: 2d6 and 2D6 mean the same thing.
Why Are Some Dice Totals More Likely Than Others?
When you roll a single die, every result is equally probable. Roll a single D6 and each of the six faces has a 1 in 6 chance of appearing.
When you add multiple dice together, the situation changes. There are 36 possible combinations when rolling 2D6, but they do not all produce different totals, and different totals do not have the same number of combinations behind them. A total of 7 can be made 6 ways, while a total of 2 can only be made 1 way.
| Total (2D6) | Combinations | Probability |
|---|---|---|
| 2 | 1 | 2.78% |
| 3 | 2 | 5.56% |
| 4 | 3 | 8.33% |
| 5 | 4 | 11.11% |
| 6 | 5 | 13.89% |
| 7 | 6 | 16.67% (most likely) |
| 8 | 5 | 13.89% |
| 9 | 4 | 11.11% |
| 10 | 3 | 8.33% |
| 11 | 2 | 5.56% |
| 12 | 1 | 2.78% |
This distribution is why 7 is the most common total in games like Backgammon and Monopoly that use 2D6. As you add more dice to a pool, the distribution of totals becomes more bell-shaped and the average grows proportionally. This is directly related to the Central Limit Theorem.
Dice Notation and Modifiers
Standard dice notation follows the format NdS+M where N is the number of dice, S is the number of sides, and M is the modifier. A modifier shifts every result up or down by a fixed amount and is applied after all dice are summed.
2d6+3: Roll two D6 dice, add the results, add 3.If the dice show 4 and 5, the dice total is 9, and the final total is 12.
1d20-2: Roll one D20, subtract 2.If the die shows 15, the final total is 13.
Advantage and Disadvantage
Advantage and disadvantage are mechanics from D&D-style games that apply to D20 rolls only. Both involve rolling two D20 dice and keeping one of the results.
| Mode | Rule | Average Result | Effect |
|---|---|---|---|
| Normal | Roll 1D20, keep it | 10.5 | Baseline |
| Advantage | Roll 2D20, keep higher | ~13.8 | Favors the player |
| Disadvantage | Roll 2D20, keep lower | ~7.2 | Disfavors the player |
Advantage raises your expected roll by more than 3 points compared to a single die; disadvantage lowers it by the same margin. This symmetry is why advantage and disadvantage cancel each other out in the ruleset they come from.
4D6 Drop Lowest: Ability Score Generation
Rolling 4D6 and dropping the lowest result is the most common method for generating character ability scores in D&D-style tabletop games. The rule exists because dropping the weakest die shifts the average and reduces the chance of very low scores, producing characters that are generally capable without being uniformly powerful.
Drop the lowest (2).
Ability score: 6 + 5 + 4 = 15
The expected value of 4D6 drop lowest is approximately 8.46, compared to 3.5 for a single D6 and 10.5 for a straight 3D6 roll. Run the batch simulation above with 4D6 and drop-lowest mode to see how scores distribute across many trials.
Dice Roller for D&D and RPGs
This virtual dice roller covers the most common dice tasks in D&D-style tabletop games:
- Attack rolls: 1D20 plus an attack modifier against a target's armor class.
- Saving throws: 1D20 plus a saving throw modifier.
- Damage rolls: weapon-specific dice like 1D8+3 or 2D6.
- Ability score generation: 4D6 drop lowest, run six times for a full character.
- Advantage and disadvantage: built into the roll mode selector.
This tool is not affiliated with or endorsed by any game publisher. The mechanics described here are generic RPG concepts used across many systems.
How Random Dice Rolls Work
This roller uses crypto.getRandomValues(), the browser's cryptographic random number API, to generate each die result. Results are mapped to integers uniformly in the range 1 through N using a rejection-sampling method that avoids modulo bias, meaning every face has exactly equal probability.
The results are entirely client-side: nothing is sent to a server. Your roll history lives only in your browser session and is cleared when you close the tab.
For more on how randomness and probability relate to statistics, see the site's introduction to basic probability and the Law of Large Numbers.
Dice Roller for Statistics and Probability
Dice make some of the best hands-on demonstrations of core probability concepts because the outcomes are discrete, countable, and immediately observable. Common classroom exercises include:
- Rolling a single D6 many times to verify that each face appears roughly 1/6 of the time.
- Rolling 2D6 repeatedly to observe the bell-shaped distribution of sums.
- Increasing the number of dice in a pool to watch the total distribution approach a normal curve, illustrating the Central Limit Theorem.
- Computing the expected value of a roll: for a D6, it is (1+2+3+4+5+6)/6 = 3.5. Compare to the Expected Value Calculator.
- Using the batch simulation to estimate probabilities empirically and compare them to theoretical calculations.
Online Dice Roller vs Physical Dice
| Feature | Online Roller | Physical Dice |
|---|---|---|
| Availability | Any device with a browser | Must carry them |
| Speed | Instant for any count | Slow for large pools |
| History tracking | Automatic | Manual |
| Custom dice | Any number of sides | Limited physical options |
| Physical feel | None | Tactile satisfaction |
| Table atmosphere | Less tactile | Traditional gaming feel |
Common Dice-Rolling Mistakes
- Confusing dice count with sides: 2D6 is two six-sided dice, not one two-sided die and one six-sided die.
- Forgetting modifiers: The modifier is separate from the dice total. Always display and track them independently.
- Assuming uniform totals: Rolling 2D6 does not produce each total from 2 to 12 with equal probability. The middle values are more likely.
- Misunderstanding advantage: Advantage applies to the D20 roll itself, before any modifier is added.
- Mixing up D100 representations: Results from 1 to 100, not 0 to 99, unless specifically using a 0-99 percentile convention.
Related Tools
Related Learning Pages
Frequently Asked Questions
An online dice roller is a browser-based tool that simulates rolling physical polyhedral dice and returns a random result. It supports standard dice used in tabletop games (D4, D6, D8, D10, D12, D20, D100) as well as custom dice with any number of sides. Everything runs in your browser with no app to install and no account needed.
Select a dice type from the dropdown or click any Quick Roll button, set the number of dice and modifier, choose a roll mode, then click Roll Dice. You can also type a notation like 2d6+3 directly into the notation field and press Roll. Results appear immediately with each individual die shown.
2D6 means two six-sided dice rolled together, with both results added to produce a total between 2 and 12. More generally, the notation NdS means N dice each with S sides. For example, 3d8 is three eight-sided dice totalling 3 to 24, and 4d6+3 is four six-sided dice plus a modifier of 3.
D20 refers to a twenty-sided die. Each roll produces a whole number from 1 to 20, with every outcome equally probable at 5%. The D20 is central to most tabletop RPG systems and is used for attack rolls, skill checks, and saving throws in D&D-style games.
You roll four D6 dice and remove the one with the lowest result. The remaining three are summed to produce an ability score. For example, rolling 6, 5, 4, 2 drops the 2, leaving 6 + 5 + 4 = 15. This method produces higher scores on average than a straight 3D6 roll and is the standard ability score generation method in D&D-style character creation.
Advantage means rolling two D20 dice and keeping the higher result. It raises the average outcome from 10.5 on a single D20 to roughly 13.8, giving the roller a statistical boost. Use the Advantage quick button or select Advantage from the roll mode dropdown.
Disadvantage means rolling two D20 dice and keeping the lower result, reducing the average outcome from 10.5 to roughly 7.2. Advantage and disadvantage are mirror images of each other and cancel out when both apply simultaneously.
This tool uses crypto.getRandomValues(), the browser's built-in cryptographic random source, combined with rejection sampling to prevent modulo bias. Every face on an N-sided die has exactly 1/N probability. No result is predetermined or predictable, making it suitable for gaming and educational probability work.
Each face on a fair D6 has probability 1/6, or approximately 16.67%. All six outcomes from 1 to 6 are equally likely on any single roll. For a deeper look at how probability works with dice, see the basic probability page.
There are 36 equally likely combinations when rolling 2D6 (6 × 6). Six of those combinations produce a total of 7: (1,6), (2,5), (3,4), (4,3), (5,2), and (6,1). No other total has as many combinations, making 7 the most probable result at 6/36 = 16.67%. In contrast, totals of 2 and 12 each have only one combination, giving them 1/36 = 2.78% probability each.
Yes. Select Custom from the dice type dropdown and enter any whole number from 2 to 1,000. The roller treats it as a fair die producing results from 1 through your chosen number, with each face equally probable.
Yes. The number-of-dice counter accepts values from 1 to 100. All dice in the pool are rolled at once and each result is displayed individually on screen, with the dice total, modifier, and final total shown separately below.
Yes. The modifier field accepts any positive or negative integer. It is added to the sum of all dice after rolling. The dice total and the modifier are always shown separately so you can see both values before the final total is calculated.
Yes. The roller covers the core dice tasks in D&D-style play: D4 through D20 for damage and checks, 4D6 drop-lowest for ability score generation, modifiers for attack and damage rolls, and advantage or disadvantage for the D20. This tool is an independent utility and is not affiliated with any game publisher.