WheelJarCall the numbers. Nothing comes up twice.
Bingo caller
Ready
—
75 numbers in the drum, none called yet
Game night, drawn
WeeklyOne game, one way to decide who starts, and one rule to change — drawn fresh each week. For the dice, cards and coin in the drawer.
Try also
What is the difference between a bingo caller and a random number generator?
Memory — a bingo drum removes each ball as it is called, and a random number generator does not. That is why the game ends: the pool shrinks, the odds of every remaining number rise, and eventually the drum is empty. A plain generator draws from the full range every time, so 42 comes up twice within a few dozen calls, and a game called that way is one nobody can win fairly.
This caller shuffles the whole range once at the start and then hands out numbers from the top of that shuffled list — the same construction a card dealer uses. Every call is therefore a number that has not been called, without any retry loop, and the count of what is left is exact rather than estimated.
The board stays on screen with the called numbers lit up, because that is what the physical board by the caller’s table is for: it settles arguments about whether 17 was called and lets a latecomer catch up.
The three formats, side by side
| Format | Numbers | Card | Letters called | Typical game |
|---|---|---|---|---|
| American | 1–75 | 5×5 with a free centre | B I N G O | Line in 15–25 calls |
| British | 1–90 | 9×3 ticket, 15 numbers | none | Three stages: line, two lines, house |
| Classroom | 1–30 | whatever you hand out | none | A few minutes |
Odds change with every call
| Numbers still in the drum | Chance the next call is a given one |
|---|---|
| 75 | 1.3% |
| 50 | 2.0% |
| 25 | 4.0% |
| 10 | 10.0% |
| 3 | 33.3% |
That is drawing without replacement in one column: nothing about the mechanism changes, only how much is left in it.
If you need repeats
For anything where the same value should be able to come up again — a raffle where the ticket goes back in, a dice-style roll, a number between one and a million — the random number generator has a no-repeats switch you can leave off. For a lottery-style line of six from forty-nine, the lottery number generator prints the odds alongside it.
Frequently asked questions
Which range should I use?
1–75 for American bingo, where the five columns are B 1–15, I 16–30, N 31–45, G 46–60 and O 61–75 — the caller says the letter with the number. 1–90 for British and Australian bingo, played on a 9×3 ticket with fifteen numbers. 1–30 is for classrooms and small groups, where a full game should take minutes rather than an hour.
Why does it say a letter before the number?
Because on a 75-ball board every number belongs to exactly one column, and calling B-7 rather than 7 tells the room which column to look in. It is not decoration — it is what makes a hall of a hundred people able to keep up. The letter only appears on the 75-ball setting, since the other formats do not use one.
How do I start a new game?
Press new game and the drum is refilled and reshuffled from scratch. Changing the range does the same thing automatically, since a half-called 75-ball game makes no sense as a 90-ball one.
Can I get the called numbers back if I reload?
No. Nothing is stored, so a reload is a new game with an empty board. For anything that matters — a charity night, a prize round — screenshot the board before you close the tab, or keep a paper list the way callers have always done.
How long does a full game take?
A single line on a 75-ball board typically falls somewhere between the fifteenth and the twenty-fifth call; a full house usually lands in the fifties. On 90-ball the numbers stretch out, which is why it is played in three stages — one line, two lines, full house — rather than as one long wait.
Is it fair for a prize game?
The draw is: every remaining number is exactly equally likely on every call, from crypto.getRandomValues. What a web page cannot give you is an audit trail, so if money is involved, have someone independent watch the screen and write the numbers down. For a draw that proves itself afterwards, the provably fair giveaway publishes a seal before the draw instead.
How the randomness works
crypto.getRandomValues with rejection sampling. Each call removes the last
number from that shuffled list, which is mathematically identical to drawing a ball from a drum and
keeping it out, and requires no checking for repeats. The board marks every called number and
highlights the most recent one. On the 75-ball setting the B-I-N-G-O letter is derived from the
number’s column: 1–15 is B, 16–30 is I, and so on. Nothing is stored between games.Worked example
With Numbers in the drum 1–75 (US bingo), this page works out —. 75 numbers in the drum, none called yet
Sources:
Drawing without replacement, in one game
Bingo is the clearest everyday example of drawing without replacement, which is why it turns up in school probability lessons long before anyone mentions the word hypergeometric. The first call has a 1-in-75 chance of being any given number; the tenth has a 1-in-66 chance, because nine balls are already out. Nothing about the drum changed — the pool did.
That shrinking pool is also why bingo feels the way it does. Early calls are almost meaningless and late calls are agonising, and the shift between the two is not psychological. With ten numbers left in the drum, each call has a one-in-ten chance of being the one on your card, which is roughly the point at which a room goes quiet.