Dice Roller
Roll d4 to d100 or dice notation like 2d6+3, or flip a coin. Runs in your browser.
About this dice roller
This dice roller rolls virtual dice from d4 to d100, or any combination you type in standard dice notation such as 2d6+3, 4d6 drop lowest or 2d20 keep highest. It is built for board games, tabletop RPGs, classroom probability and any time the real dice have rolled under the sofa.
Every roll shows each die, which dice were dropped, and the total. Below that you get the exact odds of every possible total for your notation, a history of your rolls and a count of how often each face has come up. A coin flip mode handles heads or tails.
Rolls use your browser's cryptographic random number generator with unbiased sampling, so each face is equally likely. More random tools live in the generators section.
Features
Full dice notation
Type NdS for N dice with S sides (d% means d100), add or subtract whole numbers and other dice (1d8+1d6+3), keep or drop the highest or lowest (4d6dl1, 2d20kh1, 2d20kl1), and make dice explode with ! so a top roll rolls again and adds.
Quick dice and presets
Choose how many dice, then tap d4, d6, d8, d10, d12, d20 or d100 to roll straight away. Presets cover the common cases: advantage, disadvantage, a 4d6 drop-lowest stat roll, percentile and exploding 3d6.
Exact odds for every total
For most notations the tool works out the exact probability of each total, then shows the lowest, highest and average result and your chance of rolling at least what you just rolled. Your actual rolls appear as black bars over the expected ones.
History and face counts
The latest 50 rolls are listed with their dice, and up to 2,000 are kept for the counts. A table shows how often each face of your die has come up, with its share. Roll ×100 or ×1000 to watch the counts settle towards an even split.
Coin flip
Flip 1 to 100 coins at a time, or 100 flips at once. See heads and tails totals, the heads share and the longest streak.
How to use the dice roller
- 1Tap a quick die, pick a preset, or type notation such as 2d6+3 or 2d20kh1.
- 2Press Roll or Enter to see each die and the total, or roll 100 at once.
- 3Check the odds chart, face counts and history, or switch to Coin flip.
When to use it
Tabletop RPG sessions
Roll attacks with 1d20+5, damage with 2d6+3, and advantage with 2d20kh1. Rolling up a character? Use 4d6dl1 six times for ability scores.
Board games with missing dice
Most family board games use one or two six-sided dice. Tap 2× then d6 and keep the tab open on a phone or tablet on the table.
Teaching probability
Roll 2d6 a thousand times and compare the black bars with the expected shape. Seven comes up most often, about one roll in six, and 2 or 12 only once in 36.
Settling a decision
Flip a coin, or roll a d6 with each option given a number. To draw names or split people into teams, the random picker does it in one step, and the password generator uses the same kind of secure randomness for something more serious.
How does dice notation work?
Dice notation describes a roll in a few characters. The number before the d is how many dice to roll, and the number after it is how many sides each die has. Leave out the first number and it means one die, so d20 is 1d20.
- 2d6+3: roll two six-sided dice, add them, then add 3. Range 5 to 15, average 10.
- 1d20-1: one twenty-sided die minus 1.
- 4d6dl1 (or 4d6kh3): roll four d6 and drop the lowest. The usual way to roll ability scores; it averages about 12.24.
- 2d20kh1: roll two d20 and keep the higher, called advantage. It averages 13.825 instead of 10.5.
- 2d20kl1: keep the lower, called disadvantage. It averages 7.175.
- 3d6!: exploding dice. Every 6 is rolled again and added, so totals have no fixed upper limit.
- d% or d100: a percentile roll from 1 to 100.
Why is 7 the most common roll with two dice?
Two six-sided dice have 36 equally likely combinations. Six of them add up to 7 (1+6, 2+5, 3+4 and the reverses), so 7 comes up 6 times in 36, or about 16.7%. Only one combination makes 2 and only one makes 12, so each of those has a 1 in 36 chance, about 2.8%.
The more dice you add together, the more the totals bunch in the middle. 3d6 already looks like a bell curve, which is why some games use it instead of a d20 when they want fewer extreme results.
Are online dice really random?
These ones use crypto.getRandomValues, the browser's cryptographically secure generator, rather than the faster Math.random. Each draw uses rejection sampling: random values that would make some faces slightly more likely are thrown away and drawn again, so a d6 is exactly 1 in 6 for every face.
Randomness also means streaks. Three 1s in a row on a d20 happen once in every 8,000 sets of three rolls, which is rare for one roll but not for a long campaign. A run of bad luck is not a sign the dice are broken, and past rolls never change the next one.
Why use Mavros
| Mavros | Typical upload sites | |
|---|---|---|
| Notation | NdS, +/-, keep and drop, exploding, d% | Pick a die and a count |
| Randomness | Cryptographic, unbiased sampling | Not stated |
| Odds shown | Exact probability of every total | None |
| History and face counts | Up to 2,000 rolls with per-face counts | Last roll only |
| Coin flip | 1 to 100 coins, streak and totals | Separate page |
| Ads and sign-up | None | Ads common |
Tips
- Press Enter in the notation box to roll again without reaching for the mouse.
- Use Roll ×1000 with the face count table to show students how a fair die evens out over many rolls.
- Write the modifier once in the notation, such as 1d20+7, so you never forget to add it.
- The chance of rolling X or more is handy for deciding whether a risky move is worth it.
- Clear the history before a new game so the face counts only cover that session.
Questions
How do I roll 2d6+3?
Type 2d6+3 in the notation box and press Roll or Enter. The tool shows both dice, adds them and adds 3. The result is between 5 and 15 and averages 10.
What does d20 advantage mean?
Roll two d20s and keep the higher one. Type 2d20kh1 or press the Advantage preset. It raises the average from 10.5 to 13.825.
How do I roll 4d6 drop the lowest?
Type 4d6dl1, or 4d6kh3 which means the same thing. The dropped die is shown faded and crossed out. The average is about 12.24.
Is this dice roller fair?
Yes. It uses the browser's cryptographic random generator with rejection sampling, so every face is exactly equally likely. Use Roll ×1000 and the face count table to check it yourself.
What are the odds of rolling a 7 with two dice?
6 in 36, which is 1 in 6 or about 16.7%. Seven is the most likely total because it has the most combinations. Type 2d6 to see the full chart.
What are exploding dice?
When a die shows its highest number, you roll it again and add the new roll, and keep going while it keeps maxing out. Type ! after the dice, as in 3d6!. Extra rolls show with a dashed border.
How many dice can I roll at once?
Up to 100 dice in each group, with up to 1,000 sides each and up to 10 groups or numbers joined with + and -.
Can I flip a coin?
Yes. Switch to Coin flip, choose 1 to 100 coins and press Flip. You'll see heads and tails totals, the heads percentage and the longest streak.