How does it work?
- Decide beforehand who takes heads and who takes tails (the hardest part).
- Press “Flip the coin” or the space bar: the coin spins, then lands on one side.
- The score, the longest streak and the last 20 flips stay in your browser, ready for the rematch.
What is it for?
- Sports: decide who kicks off or picks a side, like a referee.
- Games: pick who goes first, without an argument.
- Everyday life: pizza or sushi, movies or couch, when nobody can decide.
- In class: explore chance and probability with 100 flips in a few minutes.
Frequently asked questions
Is the result really random?
Yes. The side is drawn by your browser’s random generator, designed for cryptography, with exactly a one-in-two chance. The coin then spins until it reaches that side: the animation changes nothing. A real coin does slightly worse: in 2023, a team of researchers flipped 350,757 coins and found that they land on the side they started on about 51 times out of 100.
Which side is heads, and which is tails?
Heads is the side with the portrait or emblem (here, our banana). Tails is the other side, the one showing the value of the coin (here, a big 1).
I got heads 5 times in a row: is the coin rigged?
No, that’s chance! A coin has no memory: every flip starts again at one in two. In 100 flips, you are actually very likely to see a streak of 5 or more. It’s your brain that finds it fishy: it expects a regular back-and-forth, which chance doesn’t do.
Can I play best of three?
Yes: the score counts heads and tails for the game. In a best of three, the first to two points wins. “Reset” sets up the rematch.
Are my flips sent anywhere?
No. Everything happens in your browser: the score and the last flips stay there, and nothing is sent to a server.
