Coin Flip
Flip one or many virtual coins.
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Flip a single virtual coin to settle a quick decision, or flip up to 100 at once to see how many heads and tails come up and in what order. It is also a handy way to watch probability in action for a maths class.
What happens when you press Flip
Leave Number of flips blank or at 1 and you get a single result, "Heads" or "Tails". Enter a larger number and the result shows a tally such as Heads: 5 · Tails: 5 above the full sequence, for example H T T H T H T H H T. Values above 100 are capped at 100, and decimals are rounded down.
Each flip is an independent 50/50 draw from your browser's built-in pseudo-random generator. That is fair for games, toss-ups and classroom experiments, though not meant for security uses; for those, the random number generator draws from the browser's cryptographic source.
What a fair coin really produces
People expect coin results to look evenly mixed, but true randomness is streakier than intuition suggests. These probabilities apply to any fair coin:
| Outcome | Probability |
|---|---|
| Exactly 5 heads in 10 flips | 24.6% |
| Exactly 50 heads in 100 flips | 8.0% |
| Between 40 and 60 heads in 100 flips | 96.5% |
| A run of 5 or more identical results in 100 flips | 97% |
| A run of 6 or more identical results in 100 flips | 81% |
So if you flip 100 and see six heads in a row, nothing is broken. A perfectly even 50–50 split is actually the less common outcome.
The gambler's fallacy
After five tails in a row, many people feel heads is "due". It is not: the coin has no memory, and the next flip is still exactly 50/50. The long-run share of heads does drift towards half as flips pile up (the law of large numbers), but that happens because early streaks get diluted by thousands of later flips, not because the coin corrects itself.
Using a toss to decide things fairly
- Agree what heads means before anyone flips, the same way a cricket captain calls while the coin is in the air.
- For bigger stakes, agree on best of three or best of five in advance, not after seeing the first result.
- If you notice you are hoping for one side while the result loads, that preference is often the real answer.
- With more than two options, a coin is the wrong tool: the random picker chooses from a list, and the dice roller covers six or more outcomes.
Physical coins are close to fair but not perfect. Studies of real hand tosses, including a 2023 experiment with more than 350,000 flips, found a slight tendency, around 51%, for a coin to land on the same side it started on. A virtual flip has no starting side, so that bias does not apply here.