Coin flip
Heads or tails, decided by a fair random bit. Flip once to settle it, or flip thousands to see how randomness really behaves.
Tap the coin
- Heads
- 0
- Tails
- 0
- Recent
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Streaks aren’t a sign of a broken coin
Ask people to write down 100 “random” coin flips and they rarely include a run longer than four, because it feels wrong. Real sequences of 100 flips almost always contain a run of six or more. Statistics teachers use this to spot invented homework: the fake sequences alternate too much.
Over many flips, the percentage of heads settles toward 50% (the law of large numbers), even though the raw gap between heads and tails tends to grow. Flip 10,000 a few times and watch both.
Questions people ask
Is this coin flip 50/50?
Yes, exactly. Each flip takes one unbiased random bit from crypto.getRandomValues. A real coin is very slightly biased: a 2023 study by František Bartoš and colleagues, covering 350,757 flips, found coins land on the side they started on about 50.8% of the time.
Why do I get long streaks?
Streaks are normal. In 100 fair flips, the longest run of heads or tails is usually 6 or 7. People expect random results to alternate more than they really do, which is why streaks feel suspicious. Flip 100 at once and check the longest streak.
Can I flip many coins at once?
Yes, up to 10,000 per click. The page shows the heads/tails split and the longest streak so you can watch the law of large numbers pull the ratio toward 50%.