Dice Roller
Roll multiple dice with custom sides and modifiers.
Roll Result
History (Last 10)
What is a Dice Roller?
A dice roller is a virtual set of dice that generates random results in your browser, standing in for physical dice when you do not have them handy or need to roll several at once. This tool rolls between 1 and 20 dice at a time, supports anywhere from 2 to 100 sides per die, and applies an optional flat modifier to the total, so it handles everything from a simple d2 coin flip to the d20 attack rolls used in tabletop role-playing games like Dungeons & Dragons.
Every roll is independent and unpredictable because the results come from your browser's random number generator rather than a fixed pattern. The tool displays each die individually, adds the dice together with your modifier, and keeps a running history of your last ten rolls for quick reference during a game session.
The Math Behind a Dice Roll
A fair die gives every face an equal chance of landing up, so the probability of rolling any specific number is one divided by the number of sides:
P(specific face) = 1 ÷ Sides
The average (expected) value of one die is the mean of its lowest and highest faces. Expected values add together across dice, and a modifier simply shifts the total:
Average of one die = (Sides + 1) ÷ 2
Expected total = Number of Dice × (Sides + 1) ÷ 2 + Modifier
- Number of Dice — how many dice to roll together, from 1 to 20.
- Sides per Die — how many faces each die has, from 2 to 100. A standard die has 6 sides.
- Modifier — a fixed amount added to (or, if negative, subtracted from) the sum of the dice. It defaults to 0.
Worked Example: Rolling 3d6 + 2
Suppose your game calls for three six-sided dice plus a bonus of 2, written as 3d6 + 2. Set Number of Dice to 3, Sides per Die to 6, and Modifier to 2, then click Roll Dice. Say the dice come up 5, 3, and 6:
- Sum of the dice: 5 + 3 + 6 = 14.
- Add the modifier: 14 + 2 = 16 — the figure shown in the Sum + Modifier box.
You can also work out what to expect before rolling. One d6 averages (6 + 1) ÷ 2 = 3.5, so three dice average 3 × 3.5 = 10.5, and the modifier lifts the expected total to 10.5 + 2 = 12.5. The smallest possible result is 1 + 1 + 1 + 2 = 5, and the largest is 6 + 6 + 6 + 2 = 20. The chance that all three dice land on 6 is (1 ÷ 6) × (1 ÷ 6) × (1 ÷ 6) = 1 ÷ 216, or about 0.46% — roughly once in every 216 rolls.
Common Dice at a Glance
Tabletop games rely on a standard set of polyhedral dice. This table lists each die with its average roll and range:
| Die | Sides | Average Roll | Range |
|---|---|---|---|
| d4 | 4 | 2.5 | 1-4 |
| d6 | 6 | 3.5 | 1-6 |
| d8 | 8 | 4.5 | 1-8 |
| d10 | 10 | 5.5 | 1-10 |
| d12 | 12 | 6.5 | 1-12 |
| d20 | 20 | 10.5 | 1-20 |
| d100 | 100 | 50.5 | 1-100 |
2d6 Sum Probabilities
When you roll two six-sided dice together, the 36 equally likely combinations pile up around the middle totals. A sum of 7 is the single most likely outcome, while 2 and 12 are the rarest:
| Total | 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% |
| 8 | 5 | 13.89% |
| 9 | 4 | 11.11% |
| 10 | 3 | 8.33% |
| 11 | 2 | 5.56% |
| 12 | 1 | 2.78% |
How to Use
- Enter the Number of Dice you want to roll, from 1 to 20.
- Enter the Sides per Die, from 2 to 100 — 6 for standard dice, 20 for a d20.
- Enter a Modifier if you want a bonus or penalty applied to the total; leave it at 0 for a plain roll.
- Click Roll Dice. Each die appears as its own chip, and the Sum + Modifier box shows the grand total.
- Review your last ten rolls in the History panel, which is stored in your browser between visits.
Frequently Asked Questions
Is the roller truly random?
Yes. The tool uses your browser's cryptographically secure random number generator (crypto.getRandomValues) wherever it is available and falls back to Math.random only in older browsers. Every roll is independent, so previous results have no influence on the next one.
Can I roll more than 20 dice?
The limit is set to 20 dice per roll to keep the results readable, but you can roll multiple times and add the totals yourself. The History panel keeps your last 10 rolls, which makes it easy to sum several batches.
What are modifiers for?
A modifier adds or subtracts a fixed value from the total roll. Tabletop RPGs use modifiers to represent skill bonuses or penalties: a +3 modifier turns a die sum of 14 into a final result of 17. Enter a negative number for a penalty, or leave the field at 0 for a plain roll.
What is the average result of a roll?
One die averages (sides + 1) ÷ 2, so a d6 averages 3.5. Multiply by the number of dice and add your modifier: 2d6 averages 7, and 3d6 + 2 averages 12.5.
What are the odds of rolling a natural 20 on a d20?
Each face of a fair d20 has a 1 in 20 chance, so a natural 20 (or a natural 1) comes up 5% of the time — about once every 20 rolls on average.
Does the dice roller save my rolls?
Yes. The History panel stores your last 10 rolls in your browser's local storage, so they survive a page refresh. The data never leaves your device and is not shared with anyone.