Why does shaking need a button first?

Because iPhones and iPads will not report motion to a web page until you have asked for it, and the asking has to come from a tap. Press Turn shake on in the Shake tab and the browser puts the question to you. If you say no, that answer sticks until the page is reloaded, so reload and press it again. Android and desktop browsers hand motion over without asking, and the button simply switches the listener on.

Can the other players see my roll?

Only if you show them. The dice sit under the cup until you hold the peek button, and they go straight back under the moment you let go. There is no timer and no lingering screen, which is the same hold pattern the other hidden-information tools here use, because a hold is the one gesture a phone cannot perform by accident in somebody else's hand.

Is the roll fair, or does the rattle decide it?

The faces are drawn the instant you shake, from the browser's cryptographic random number generator, and the rattle is decoration played afterwards. Every face really is one in six and every die is independent. Nothing watches how hard you shook, so a gentle shake and a violent one give exactly the same distribution.

Does it stop somebody rolling twice until they like the result?

No, and no cup can. It keeps one roll at a time and covers whatever was showing the moment a new roll starts, so a second roll is visible to the table as a second shake. Bluffing games have always leaned on players watching each other, and that part still works the way it always did.

Can I use it for a game with more dice?

Six is the limit here because a cup you cannot read at a glance is not much use. For larger handfuls, more sides, or a pool you keep and reroll, the plain dice roller takes many more dice and every common die.

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Dice cup

Shake to roll, lift to look, cover to hide. Bluffing games on one phone.

Made by the PaperCarnival team · Updated 2026-09-22

5 dice, ready

Shake the cup to roll.

How many dice

Five is the usual number for bluffing games. The faces are drawn the moment you shake, before the cup rattles, so what is under it never changes while you decide whether to look.

Nothing rolled yet.

The oldest hidden information in games

A great many dice games turn on one idea: you know what is under your cup and nobody else does. Players take it in turns to claim how many dice of a given face are on the table across every cup, each claim has to beat the last, and somebody eventually calls the claim a lie. Then the cups come up. Whoever was wrong loses a die, and the game gets smaller until one player is left holding dice.

You do not need any particular set of rules to use this. It is a cup, five dice and a lid, which covers that whole family as well as the simpler versions where you just want a roll nobody else has seen yet.

Shaking the device, tapping the button and pressing a key all pull from the same draw, so how you roll decides nothing, and if motion is unavailable the button is the whole tool. For an open roll everybody watches, the dice tower puts the clatter on screen instead of under a cup.

Kept in this browser under pph.cup.count, pph.cup.motion and pph.cup.muted, and nowhere else. Accounts, printing, storage and what the page loads are answered on the FAQ.

Questions

Why does shaking need a button first?: Because iPhones and iPads will not report motion to a web page until you have asked for it, and the asking has to come from a tap. Press Turn shake on in the Shake tab and the browser puts the question to you. If you say no, that answer sticks until the page is reloaded, so reload and press it again. Android and desktop browsers hand motion over without asking, and the button simply switches the listener on.
Can the other players see my roll?: Only if you show them. The dice sit under the cup until you hold the peek button, and they go straight back under the moment you let go. There is no timer and no lingering screen, which is the same hold pattern the other hidden-information tools here use, because a hold is the one gesture a phone cannot perform by accident in somebody else's hand.
Is the roll fair, or does the rattle decide it?: The faces are drawn the instant you shake, from the browser's cryptographic random number generator, and the rattle is decoration played afterwards. Every face really is one in six and every die is independent. Nothing watches how hard you shook, so a gentle shake and a violent one give exactly the same distribution.
Does it stop somebody rolling twice until they like the result?: No, and no cup can. It keeps one roll at a time and covers whatever was showing the moment a new roll starts, so a second roll is visible to the table as a second shake. Bluffing games have always leaned on players watching each other, and that part still works the way it always did.
Can I use it for a game with more dice?: Six is the limit here because a cup you cannot read at a glance is not much use. For larger handfuls, more sides, or a pool you keep and reroll, the plain dice roller takes many more dice and every common die.

Dice cup

The oldest hidden information in games

Questions

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