WheelJarCoins, Dice & Cards
The classic randomisers — a coin, a handful of dice, a deck of cards — without needing to own any of them.
Card dealer for players
Drawing one card is easy. Dealing five people five each without a repeat is the hard part.
Dice bag: mixed dice
2d6 plus a d8 plus four. Nobody adds that up right at half past eleven.
Coin flip
A real coin is caught same-side-up 51% of the time. This one has no such habit.
D20 roller
One twenty-sided die, two if you have advantage. The maths behind the swing is stark.
Dice roller
Two d6 by default, anything from d4 to d100 on request. No dice under the sofa.
Random card generator
Fifty-two cards, one honest shuffle, and no card ever turning up twice in the same draw.
Coins, dice and cards are the randomisers people already trust, which is why they survive on a screen. Nobody needs the rules explained, and nobody argues about what a six means.
Choose by the shape of the answer you need. Two outcomes is a coin flip, and the digital version is genuinely better than the metal one — a real coin caught in the hand favours its starting face at around 51% in theory, and at 50.8% across 350,757 recorded flips in 2023. A small numbered range is the dice roller, covering d4 through d100 with up to ten dice and their total. Tabletop play with advantage and disadvantage is the d20 roller, where keeping the higher of two dice lifts the average from 10.5 to about 13.82. And 52 outcomes with four overlapping ways to group them is the random card draw — red or black for a 50/50, suit for a four-way split, high card to settle a tie between any number of people.
What none of them do is remember. Each flip, roll and draw is independent, so streaks happen and mean nothing. The reasoning behind all of it is in how random is random, and the physical coin story is in is a coin flip really 50/50.
Frequently asked questions
Are digital dice and coins as fair as physical ones?
Fairer, in measurable ways. A caught coin lands the same side up about 51% of the time because of how it precesses in flight, and cheap plastic dice carry bubbles and uneven trimming that skew the faces. A cryptographic draw has no physics to go wrong. What it loses is the ritual, which for some games is the entire point.
Which page do I want for tabletop games?
The d20 roller if you need advantage and disadvantage, since it rolls two dice and keeps the higher or lower for you. The dice roller for everything else — any die from d4 to d100, up to ten at once, with the total added up. Both draw each die independently rather than deriving several from one number.
Can the same card be drawn twice?
Not within one draw. The random card page shuffles the whole deck with Fisher–Yates and deals off the top, so ten cards means ten different cards exactly as it would with a physical deck. Press draw again and the deck is reshuffled from all 52, so cards from a previous draw can certainly reappear.
Why did I get five heads in a row?
Because that happens about one time in 32, and in a hundred flips it would be strange if it did not. Each flip, roll and draw is independent, with no balancing mechanism trying to even the score — a generator that corrected for streaks would be predictable, which is the one thing a random source must never be.
How the randomness works
crypto.getRandomValues, the browser’s cryptographically
secure generator, and use rejection sampling to land in range — the leftover values that would
make low results marginally more likely under a naive modulo are discarded and redrawn. Multiple
dice and multiple coins each get their own independent draw. The card deck is shuffled with
Fisher–Yates so every ordering of the 52 cards is equally likely, then dealt from the top, which
is why duplicates within a draw are impossible. Nothing is stored between rolls and nothing is
ever sent to a server.Sources: