Is this dice roller truly random?

The values come from crypto.getRandomValues, the browser's cryptographic generator, and not from Math.random. There is a second step that matters just as much: a byte holds 256 values and 256 is not a multiple of 6, so mapping a byte straight onto a d6 with a remainder would make faces 1 to 4 come up 43 times per 256 bytes and faces 5 and 6 only 42. This roller throws away the values that do not divide evenly and draws again, which is called rejection sampling. The result is that every face is exactly equally likely, and the test suite checks it by sweeping all 256 byte values through every die.

How do advantage and disadvantage work?

Advantage rolls the d20 twice and takes the higher result; disadvantage rolls twice and takes the lower. Both dice are shown, with the one that was not taken dimmed, because the die you did not use is half of what makes the roll worth seeing. The setting applies to every d20 in the roll and leaves other dice alone: rolling 1d20 alongside 2d6 of damage throws each d6 once and the d20 twice. A tie keeps one die and dims the other.

Does it work for D&D 5e and other tabletop RPGs?

Yes, for any game that uses the standard polyhedral dice. D&D 5e advantage and disadvantage, 4d6 drop lowest for ability scores, and the natural 20 and natural 1 callouts are built in, and the same dice serve D&D 3.5, Pathfinder and most other d20 games. It rolls dice only: it does not keep a character sheet, track hit points or count successes in a dice pool. Systems with their own symbol dice, such as Fate dice or the Star Wars narrative dice, are not on the tray.

How do I roll 4d6 drop lowest for stats?

Tap d6 four times, then put 1 in the Drop lowest box and press Roll. All four values are shown and the smallest one is dimmed and left out of the total. If two dice tie for lowest, only one of them is dropped. Drop lowest reaches across every die in the roll rather than one group at a time, and it runs after advantage has picked its d20, so a discarded advantage die is never counted as one of the dice you asked to drop.

Does it tell me when I roll a natural 20?

Yes. A 20 on a d20 is called out under the total, and so is a natural 1. It is the value on the die itself, before the modifier, and only on a d20: a 20 rolled on a d100 is not a natural 20, and a 1 on a d6 is not a natural 1. A 20 that advantage or disadvantage discarded does not count either, since that die is not the one that was used.

Can I roll a d100 or percentile dice?

Yes, d100 is on the tray alongside d4, d6, d8, d10, d12 and d20. It is a true 1 to 100 draw, the same result a percentile roll gives, rather than two d10s read as tens and units, so every value from 1 to 100 is exactly one in a hundred. You can mix dice freely, up to 100 dice in a single roll, and the roll is labelled in dice notation, for example 2d6 + 1d20 + 3.

Can I roll a d3, a d5, a d30 or a die with any number of sides?

Yes. Type the number of sides into the custom die at the end of the tray, anything from 2 to 1000, then press its plus to add it to the roll. A d3 rolls 1 to 3 and a d30 rolls 1 to 30, with every face exactly as likely as any other, using the same rejection sampling as the standard dice. The custom die mixes with the rest, so 1d20 + 2d3 is one roll. A number the tray already has, such as 6 or 20, points you to that die instead.

How is this different from the random number generator here?

The random number generator takes dice notation you type, like 3d6+2, and is built for picking numbers and drawing names. This one is a tray: you tap the dice, see them drawn face by face, and get the tabletop mechanics that notation alone cannot express, namely advantage, disadvantage, drop lowest, natural 20 and 1, and a running log of what was rolled. Both use the same cryptographic randomness.

Does it work on a phone?

Yes. It runs in any current browser on an Android phone, an iPhone, a tablet or a computer, with nothing to download or install and no account. On small screens the dice buttons grow to finger size, and your tray and roll log are remembered in that browser for next time.

Is my roll log stored anywhere?

Not on any server. Everything runs in your browser, nothing is uploaded, and there is no account. The last 50 rolls and your current dice selection are remembered in this browser's local storage so the tray is where you left it when you come back. Pressing Clear removes the log, and clearing your browser's site data removes it too.

Dice Roller

Tap the dice you want and roll them: the full D&D set from d4 through d20 and d100, a custom die with any number of sides from 2 to 1000, a modifier, advantage or disadvantage on the d20, and drop lowest for stat rolls. Every face that came up is drawn, not just the total, including the die that advantage discarded and the one that drop lowest removed, and d6 faces show their dots. Two matching dice are called out as doubles, and the last 50 rolls stay in a log you can copy.

1d20Press Roll, the space bar or R.

Dice

Modifier

d20

Drop lowest

Tap a die to add it to the roll, then press Roll, the space bar or R.

Every die is shown, because the total is not the whole answer. A natural 20 matters, advantage means the higher of two dice, and drop lowest cannot be trusted unless the die that was dropped is on screen. Faces come from crypto.getRandomValues rather than Math.random.

Common questions

Is this dice roller truly random?: The values come from crypto.getRandomValues, the browser's cryptographic generator, and not from Math.random. There is a second step that matters just as much: a byte holds 256 values and 256 is not a multiple of 6, so mapping a byte straight onto a d6 with a remainder would make faces 1 to 4 come up 43 times per 256 bytes and faces 5 and 6 only 42. This roller throws away the values that do not divide evenly and draws again, which is called rejection sampling. The result is that every face is exactly equally likely, and the test suite checks it by sweeping all 256 byte values through every die.
How do advantage and disadvantage work?: Advantage rolls the d20 twice and takes the higher result; disadvantage rolls twice and takes the lower. Both dice are shown, with the one that was not taken dimmed, because the die you did not use is half of what makes the roll worth seeing. The setting applies to every d20 in the roll and leaves other dice alone: rolling 1d20 alongside 2d6 of damage throws each d6 once and the d20 twice. A tie keeps one die and dims the other.
Does it work for D&D 5e and other tabletop RPGs?: Yes, for any game that uses the standard polyhedral dice. D&D 5e advantage and disadvantage, 4d6 drop lowest for ability scores, and the natural 20 and natural 1 callouts are built in, and the same dice serve D&D 3.5, Pathfinder and most other d20 games. It rolls dice only: it does not keep a character sheet, track hit points or count successes in a dice pool. Systems with their own symbol dice, such as Fate dice or the Star Wars narrative dice, are not on the tray.
How do I roll 4d6 drop lowest for stats?: Tap d6 four times, then put 1 in the Drop lowest box and press Roll. All four values are shown and the smallest one is dimmed and left out of the total. If two dice tie for lowest, only one of them is dropped. Drop lowest reaches across every die in the roll rather than one group at a time, and it runs after advantage has picked its d20, so a discarded advantage die is never counted as one of the dice you asked to drop.
Does it tell me when I roll a natural 20?: Yes. A 20 on a d20 is called out under the total, and so is a natural 1. It is the value on the die itself, before the modifier, and only on a d20: a 20 rolled on a d100 is not a natural 20, and a 1 on a d6 is not a natural 1. A 20 that advantage or disadvantage discarded does not count either, since that die is not the one that was used.
Can I roll a d100 or percentile dice?: Yes, d100 is on the tray alongside d4, d6, d8, d10, d12 and d20. It is a true 1 to 100 draw, the same result a percentile roll gives, rather than two d10s read as tens and units, so every value from 1 to 100 is exactly one in a hundred. You can mix dice freely, up to 100 dice in a single roll, and the roll is labelled in dice notation, for example 2d6 + 1d20 + 3.
Can I roll a d3, a d5, a d30 or a die with any number of sides?: Yes. Type the number of sides into the custom die at the end of the tray, anything from 2 to 1000, then press its plus to add it to the roll. A d3 rolls 1 to 3 and a d30 rolls 1 to 30, with every face exactly as likely as any other, using the same rejection sampling as the standard dice. The custom die mixes with the rest, so 1d20 + 2d3 is one roll. A number the tray already has, such as 6 or 20, points you to that die instead.
How is this different from the random number generator here?: The random number generator takes dice notation you type, like 3d6+2, and is built for picking numbers and drawing names. This one is a tray: you tap the dice, see them drawn face by face, and get the tabletop mechanics that notation alone cannot express, namely advantage, disadvantage, drop lowest, natural 20 and 1, and a running log of what was rolled. Both use the same cryptographic randomness.
Does it work on a phone?: Yes. It runs in any current browser on an Android phone, an iPhone, a tablet or a computer, with nothing to download or install and no account. On small screens the dice buttons grow to finger size, and your tray and roll log are remembered in that browser for next time.
Is my roll log stored anywhere?: Not on any server. Everything runs in your browser, nothing is uploaded, and there is no account. The last 50 rolls and your current dice selection are remembered in this browser's local storage so the tray is where you left it when you come back. Pressing Clear removes the log, and clearing your browser's site data removes it too.

Every face is equally likely: values come from the browser's cryptographic generator with rejection sampling, so a d6 is exactly one in six on each face. The log is kept in this browser only.