Dice Roller
Pick a die, d4, d6, d8, d10, d12, d20 or d100, or choose Custom sides and enter any whole number of sides from 2 to 1,000. Enter the number of dice, from 1 to 20, and a modifier if you need one, such as 2 or -1. Press Roll. You see the face of each die and, when you roll two or more or use a modifier, the total. Below that are the lowest and highest possible totals and the average. Up to four earlier throws stay listed underneath with their totals.
How to use the Dice Roller
- Enter your numbers in the Dice Roller above.
- Press the Roll button to see the result.
- To try other numbers, change any value and press the button again.
The dice rolling probability
One die: P(any one face) = 1 / sides · · · Average of one die = (sides + 1) / 2 · · · Average total = dice × (sides + 1) / 2 + modifier
Every face of a die is equally likely. The roller picks each face with JavaScript's Math.random, so a d6 lands on each number about one time in six. Totals of several dice are not equally likely. Middle totals come up more often than the extremes, because more combinations add up to them.
Worked example
Roll 3d6, three six-sided dice. The total runs from 3 to 18 and averages 10.5. Of the 216 equally likely outcomes, 27 add up to 10 and 27 to 11, so a 10 or 11 comes up 25% of the time. Only one outcome makes 18, a chance of 1 in 216 or about 0.46%, and the same goes for 3. Now a custom roll, 3d7+2: three seven-sided dice plus 2. The calculator shows possible totals of 5 to 23 and an average of 14, which is 3 × (7 + 1) / 2 + 2.
Frequently asked questions
How random is the result?
Each die comes from JavaScript's Math.random(), a pseudo-random number generator. That is fine for games and classroom simulations. It is not meant for security uses such as passwords.
How do I roll with advantage or disadvantage?
Choose d20 and 2 dice, then press Roll. With advantage you keep the higher of the two numbers, with disadvantage the lower. The roller shows both dice and leaves the choice to you. Over all 400 possible pairs the higher die averages 13.825 and the lower one 7.175, against 10.5 for a single d20.
Can I roll a custom die?
Yes. Choose Custom sides and enter a whole number from 2 to 1,000. Each face has the same chance, so a d7 shows each number one time in seven on average. The menu also has the seven standard dice: d4, d6, d8, d10, d12, d20 and d100. A d100 roll is one number from 1 to 100.
How does the modifier work?
It is added once to the total, not to each die. 2d6 with a modifier of 3 gives totals of 5 to 15. A negative modifier subtracts, and a total can go below 0. The faces of the dice stay as rolled, and the modifier can be any whole number from -1,000 to 1,000.
How many dice can I roll at once?
From 1 to 20 dice of one type. For more, or to mix types such as a d20 and a d6, roll twice. The earlier throw stays in the list below.