Coin Flip
The coin above lands heads or tails with an even chance each time. The pages under it flip several coins at once and count the results, from two flips up to a thousand.
Flip it
Each flip is an independent 50/50 draw from your browser's random number generator. A run of five or six the same way is normal in 100 flips — that is what surprises people most.
Every page in this section
- Yes or NoA single answer, and a short honest note on why a coin is a fine way to decide something y
- Flip 3 Coins at Once3 flips at once with the running tally, the longest streak, and the sequence as copyable t
- Flip 10 Coins at Once10 flips at once with the running tally, the longest streak, and the sequence as copyable
- Flip 5 Coins at Once5 flips at once with the running tally, the longest streak, and the sequence as copyable t
- Flip 50 Coins at Once50 flips at once with the running tally, the longest streak, and the sequence as copyable
- Flip 2 Coins at Once2 flips at once with the running tally, the longest streak, and the sequence as copyable t
- Flip 20 Coins at Once20 flips at once with the running tally, the longest streak, and the sequence as copyable
- Flip 100 Coins at Once100 flips at once with the running tally, the longest streak, and the sequence as copyable
- Flip 1000 Coins at Once1000 flips at once with the running tally, the longest streak, and the sequence as copyabl
- Heads or TailsThe flip itself, plus what the odds really are on a real coin
The odds, exactly
One flip is 50 per cent heads, 50 per cent tails. Two flips give four equally likely orders, so two heads happens once in four. Three flips give eight orders, so three heads in a row is 1 in 8, or 12.5 per cent. Each extra coin halves the chance of an unbroken run.
Streaks are ordinary, not evidence
Flip twenty times and a run of five or more identical results appears somewhere in the sequence 45.8 per cent of the time. In ten flips, a run of four or more turns up 46.5 per cent of the time. That is close to half in both cases. A streak on twenty flips is what a fair coin looks like, and over a thousand flips a run of ten identical results is more likely than not, at 62 per cent.
Nothing is ever due
After six heads the next flip is still 50/50. The coin holds no record of the six. What is true is that a run gets diluted rather than corrected: keep flipping and the six are outnumbered by later flips, so the average drifts back towards half. Tails are never owed.
Even splits are rarer than people expect
Ten flips land on exactly five heads only 24.6 per cent of the time. Twenty flips land on exactly ten heads 17.6 per cent of the time. The even split is still the single most likely result, and it still loses to everything else put together, which is why ten flips so often reads 6-4 or 7-3.
Real coins are slightly unfair
A tossed and caught coin carries a small same-side bias. A 2023 study of 350,757 human tosses found the coin landed on the side that started facing up about 50.8 per cent of the time, caused by wobble in the toss rather than a weighted coin. Spinning a coin on a table is worse. The tool above has no physical bias at all.