Coin flip

How to flip a coin online

Hit Flip the coin and watch it spin before landing on heads or tails. One flip settles most arguments, but this coin is built for the times one flip is not enough. A running tally counts heads, tails, and total flips, and shows the split as a percentage so you can watch it drift toward even as the flips add up. The last two dozen results stay on screen as a history strip, so nobody has to remember what happened three flips ago.

How the coin flipper works: real randomness

Every flip is decided by your device’s cryptographic random number generator, the same crypto.getRandomValues source browsers use for security-sensitive work, rather than the weakerMath.random where it can be avoided. The tool draws a random value and uses rejection sampling to strip out modulo bias, so heads and tails each land with a true one-in-two chance and neither side is even slightly favored. It all runs client-side in your browser tab: nothing is uploaded, nothing is stored on a server, and once the page has loaded you can keep flipping offline. There is no account and nothing to install.

Run a best of 3, 5, or 7

Switch Series mode to Best of 3, Best of 5, or Best of 7 and the coin starts keeping score for you. A best of five goes to the first side that reaches three wins, so the series ends as soon as the result is mathematically settled rather than dragging through all five flips. The tool announces the winner and the score, then waits for you to start a new series. The lifetime tally keeps running underneath, so you can play a dozen series and still see the overall split.

Streaks, and why they look wrong

The streak panel shows your current run and the longest run of heads and of tails so far. Long runs feel suspicious, but they are exactly what genuine randomness produces: in twenty flips, a run of four or more is more likely than not. A coin has no memory, so five heads in a row does not make tails due on the sixth. Expecting it to even out on the very next flip is the gambler’s fallacy, and it is the single most common mistake people make about coins.

The odds of a streak: five heads in a row

Because each flip is independent, the chance of a run is just one half multiplied by itself once per flip. Two heads in a row is a one in four shot, and every extra head halves the odds again. Five heads in a row comes out to one in thirty-two, a little over three percent, which is uncommon but far from miraculous over a long session.

Is a real coin toss actually 50/50?

Almost, but not exactly. A 2023 study of 350,757 real coin tosses found that a flipped coin lands the same side up it started about 50.8 percent of the time, close to the 51 percent that statistician Persi Diaconis and colleagues predicted back in 2007. The cause is physical: a human thumb makes the coin wobble slightly as it spins, so it spends a touch more time with its starting face upward. Cover the coin’s starting side and even that small edge disappears. A virtual flip has no thumb and no wobble, so this one is a clean 50/50.

A short history of heads or tails

Deciding by coin is ancient. The Romans played a game called navia aut caput, ship or head, named for the images stamped on their bronze coins, and a favorable toss was read as the will of the gods. The English “heads or tails” simply points at the two faces of a coin: the portrait side and the reverse. Over the centuries the toss became the neutral referee of choice precisely because it is so hard to rig in the open, which is why it still opens football matches, starts cricket innings, and has decided everything from disputed elections to the seating of tied candidates. The most watched coin toss of the year is the one before the Super Bowl, wagered on by millions purely for fun. A flip carries no strategy and no memory, and that blankness is the whole point: it hands the decision to chance so no person has to own it.

Flip more than one coin

Need to flip several coins at once? Open the multi-coin pages to see how the odds change as coins add up: flip 2 coins where one of each is the most likely result, flip 3 coins for a built-in random majority, or flip 100 coins to watch the law of large numbers pull the count toward fifty heads.

Where a coin flip helps

A coin flip is the fastest way to break a tie between two options: who kicks off, who picks the restaurant, who takes out the trash. It works for group decisions too, since everyone can watch the same flip and agree on the outcome without anyone touching a real coin. There is also a well-known trick for using it on yourself: assign your two options to heads and tails, flip, and pay attention to the flash of feeling when it lands. A pang of disappointment tells you which option you were quietly hoping for, so even a coin you overrule has done its job. For more than two options, hand the choice to the spinner wheel instead.

Frequently asked questions