Random tools · Free tool
Online Dice Roller: Roll Any Dice, With Exact Odds of Your Total
Quick answer
Pick a die (d4, d6, d8, d10, d12, d20 or d100), choose how many to roll, add a modifier if you need one and press Roll. The roller shows every die, the total, and the exact chance of rolling that total or higher. For a d20 you can roll with advantage or disadvantage.
| Dice | d4, d6, d8, d10, d12, d20, d100; up to 50 at once |
|---|---|
| Modifiers | Any whole number, positive or negative |
| d20 advantage | Chance of a natural 20 rises from 5% to 9.75% |
| Odds shown | Exact, worked out from every possible combination |
| Randomness | crypto.getRandomValues, no modulo bias |
This online dice roller handles every die you need for D&D, tabletop RPGs and board games. Choose a die, set how many to roll, add a modifier and press Roll. Besides the result, you get something most dice rollers don't show: the exact chance of rolling your total or higher.
Roll the dice
1d20
?
Which dice can you roll?
| Die | Faces | Common use | Average roll | Chance of max |
|---|---|---|---|---|
| d4 | 1–4 | Small weapon damage, healing potions | 2.5 | 25% |
| d6 | 1–6 | Board games, fireball damage, stats | 3.5 | 16.67% |
| d8 | 1–8 | Longswords, hit dice | 4.5 | 12.5% |
| d10 | 1–10 | Heavy weapons, percentile pairs | 5.5 | 10% |
| d12 | 1–12 | Greataxes, barbarian hit dice | 6.5 | 8.33% |
| d20 | 1–20 | Attacks, saving throws, ability checks | 10.5 | 5% |
| d100 | 1–100 | Percentile tables, random encounters | 50.5 | 1% |
The average of one die is (1 + number of faces) ÷ 2. For several dice, multiply by the number of dice: 8d6 averages 28.
How the odds of your total are calculated
For one die, every face has the same chance: 1 in the number of sides. For several dice, the roller counts every combination that produces each total. With two d6 there are 36 combinations, and six of them make 7, so a 7 comes up 6 ÷ 36 = 16.67% of the time. With 8d6 there are 1,679,616 combinations; the roller counts them all in a fraction of a second, so the probabilities you see are exact, not estimates.
P(total) = combinations that make the total ÷ sides^dice3d6: 27 of the 216 combinations add up to 10, so P(10) = 27 ÷ 216 = 12.5%. Only one makes 18, so P(18) = 1 ÷ 216 ≈ 0.46%.
That's why big sums of dice cluster around the middle. One d20 is flat: a 2 is as likely as a 19. But 3d6 forms a bell curve, with 10 and 11 the most common totals and 3 or 18 rare.
Advantage and disadvantage on a d20
D&D 5th edition uses advantage (roll two d20s, keep the higher) and disadvantage (keep the lower). It changes the odds more than many players think:
| You need | Normal | With advantage | With disadvantage |
|---|---|---|---|
| 10 or more | 55% | 79.75% | 30.25% |
| 15 or more | 30% | 51% | 9% |
| 20 (natural 20) | 5% | 9.75% | 0.25% |
P(at least k with advantage) = 1 − ((k − 1) ÷ 20)²Needing 15: 1 − (14/20)² = 1 − 0.49 = 51%. With disadvantage it's ((21 − k) ÷ 20)² = (6/20)² = 9%.
On average, advantage is worth about +3.3 on a single roll: the average result rises from 10.5 to 13.825, and disadvantage drops it to 7.175.
Rolling stats: 4d6, drop the lowest
A popular way to roll D&D ability scores is to roll four d6 and drop the lowest die. Counting all 1,296 combinations gives an average of about 12.24 per stat. The chance of an 18 is 21 in 1,296, about 1.62%, and roughly 23% of stats come out at 15 or higher. To use it here, roll 4d6 and drop the smallest die yourself.
Are online dice fair?
Physical dice are rarely perfect. Cheap dice can favour some faces because of uneven pips, air bubbles or rounded edges. This roller uses your browser's cryptographic random generator, the same source used for encryption, and rejects the few raw values that would make some faces more likely than others. Every face has exactly the same chance, and no roll depends on the last.
If you play dice games for money, fairness isn't the same as good odds. A fair d6 still gives the house an edge when a game pays 4 to 1 on a 1-in-6 chance. Our dice odds calculator shows how payouts and probabilities combine into the house edge.
More random tools
- Random number 1–20 and 1–6 for quick single rolls
- Coin flip for heads or tails
- Farkle score calculator and Yahtzee odds for classic dice games
Frequently asked questions
Is an online dice roller as fair as real dice?
It's fairer than most real dice. Physical dice can be slightly unbalanced by uneven drilling for the pips or rounded edges. This roller uses your browser's cryptographic random generator and gives every face exactly the same chance.
What are the odds of rolling a natural 20 with advantage?
With advantage you roll two d20s and keep the higher, so you only miss a 20 if both dice miss: (19/20)² = 90.25%. The chance of at least one 20 is 1 − 0.9025 = 9.75%, almost double the normal 5%.
What does 2d6 + 3 mean?
Roll two six-sided dice, add them together, then add 3. The roller accepts the same notation: choose d6, set the number of dice to 2 and the modifier to 3.
What's the most likely total with two six-sided dice?
Seven. Six of the 36 combinations add up to 7, so it comes up 16.67% of the time. Totals of 2 and 12 each have only one combination, a 2.78% chance.
How do I roll 4d6 and drop the lowest for D&D stats?
Roll four d6 and ignore the lowest die. On average that gives about 12.24 per stat. The chance of an 18 is 21 in 1,296, about 1.62%, and the chance of 15 or more is about 23.15%.
Sources
- Crypto: getRandomValues() method — MDN Web Docs
- Two Basic Rules of Probability — OpenStax, Rice University. Multiplication rule; independent events