Flip a coin

Each flip is one bit from crypto.getRandomValues, the browser's cryptographic source: heads when it is 1, tails when it is 0, exactly even odds and no memory of the flip before. A thousand flips are a thousand separate bits, not one number spread out. That is a fairer coin than the one in your pocket. Real coins lean slightly towards landing the way they started — a 2023 study of over 350,000 hand-tossed flips found about 50.8% came down on the starting face — so a person who knows which side is up has a small edge. Here there is no starting face.

Streaks surprise people, and they should not. In a hundred fair flips the longest run of one face is usually six or seven, and a run of eight or more happens in roughly a third of all hundred-flip sessions. The page prints the longest run and works out, exactly, how often a fair coin produces a run that long in a session that size, so you can see how ordinary it is. It also does not balance itself: after five heads, the next flip is still exactly fifty-fifty, and a tally that drifts away from half-and-half over a short session is chance, not a fault.

The tally since reset lives in this tab only and is gone when it closes. Nothing is sent and nothing is stored; the Dark button keeps its own setting in this browser's local storage.