Coin flip
Nothing yet. Results appear here so you can prove what came up.
A coin flip gives heads or tails with equal probability. This one draws from the browser’s cryptographic random number generator rather than a simple pseudo-random function, so the two outcomes really are equally likely. Flip once, or flip several hundred at a time and watch the tally converge on fifty–fifty.
How to flip
A real coin is not quite fair. Persi Diaconis and colleagues showed in 2007 that a flipped coin lands the same way up as it started about 51% of the time, because it precesses rather than rotating cleanly. A digital flip has no such bias, which makes it the fairer of the two even though it feels less trustworthy.
What people use it for
- Settling who goes first, or who takes the job nobody wants
- Flipping when there is no coin in anybody’s pocket
- Watching a tally drift towards even over a few hundred flips at once
- Running a two-way draw someone else can reproduce from the seed
- Showing that six heads in a row changes nothing about the seventh
Questions
Each flip comes from crypto.getRandomValues, the browser’s cryptographically secure generator, mapped to two outcomes with rejection sampling so neither side is favoured.
Entering a seed switches to a deterministic generator, so the same seed always produces the same sequence. It is how you let someone else verify a draw.
Because it should not be. Over a hundred flips a split of 55–45 is entirely ordinary. The proportion converges slowly; the raw difference does not converge at all.
No. Each is independent, and a run of six heads does not make tails any likelier. Expecting otherwise is the gambler’s fallacy.