Coin Flip

Flip one or many coins and tally heads and tails. Free, runs entirely in your browser — no signup, and nothing you paste in is uploaded.

Flipping many coins is the cleanest illustration of how randomness actually behaves. A long run of heads is not evidence that tails is due — each flip is independent, and the gambler's fallacy is exactly the intuition that it is not.

What does happen is that the *proportion* converges while the absolute difference tends to grow. Ten flips landing 7–3 is unremarkable; ten thousand landing 7000–3000 would be extraordinary. Watching the tally is a faster way to internalise that than reading it.