Coin Flip

How to flip a coin

1. Press Flip the coin (or click the coin itself). The coin is tossed, spins and lands on Heads or Tails, and the result is written below it.
2. To flip several coins in one go, change Coins per flip (up to 10,000). The coin shows the last result, and This flip lists every coin in the order it was flipped, with the number of heads and tails.
3. The statistics update after every flip: Total flips, the number and percentage of Heads and Tails, the Heads : tails ratio, the Current streak, the Longest heads streak and Longest tails streak, and the Chance of this streak. The bar under the statistics shows the share of heads at a glance.
4. The History (newest first) shows the last 500 results as small H and T badges. Copy copies the whole sequence as a line of letters, oldest first, which is handy for a class experiment or a spreadsheet.
5. Reset statistics starts again from zero.

Untick Animate the coin if you just want the answer. When your device asks for reduced motion, the coin lands instantly without spinning.

Is it a fair coin?

Yes, and fairer than most real coins. Each flip uses your browser’s cryptographic random number generator (the Web Crypto API) to draw one random bit: heads and tails each have exactly a 50% chance, and every flip is independent of the ones before it. The result is chosen as soon as you press the button; the spinning animation simply turns the coin to the side that was drawn. Nothing is sent to a server.

Real coins are close to fair but not perfect. A large 2023 study of more than 350,000 hand-flipped coins found that a coin lands on the same side it started on about 51% of the time. A virtual coin has no starting side, no weight and no thumb.

Streaks and the gambler’s fallacy

Long streaks feel suspicious, but they are normal. In 100 flips, a run of six or seven identical results in a row is typical. After five heads in a row, the next flip is still 50/50: the coin has no memory. Believing that tails is now “due” is known as the gambler’s fallacy.

The Chance of this streak shows how unlikely the current streak was once it started: after the first result, each further flip matches it with probability 1/2. A streak of 5 therefore has a 1 in 16 chance (1/2 × 1/2 × 1/2 × 1/2). Over many flips, the share of heads drifts toward 50%, but the difference in raw counts can still grow; that is the law of large numbers at work.

Ideas for using it

• Decide who kicks off, who serves first or who picks first.
• Settle a friendly argument or choose between two options.
• Run a probability lesson: flip 1,000 coins at once, compare the percentage with 50%, and look at the longest streaks.