Heads or tails
Need to make a call and there's no coin in your pocket? Flip one here: animation, instant result, and session stats.
Is a coin flip really 50/50?
With this virtual coin, yes: each flip has exactly a 50% chance per side, because the result comes from the browser's random number generator. Real coins are another story, a 2023 study of more than 350,000 tosses measured a slight bias (about 51%) toward landing on whichever side was facing up at launch. So the digital version is actually fairer than the physical one.
Watch out for streaks: the gambler's fallacy
Four heads in a row doesn't make tails "due": every flip is independent and always starts fresh at 50%. That's exactly what the longest-streak stat above is there to show, over twenty or so flips, a run of 4 or 5 identical results is completely normal, not a sign that the coin is rigged.
Why a real coin is not fifty-fifty
On this page it is, because the result comes from a generator with no memory and no preferences. A metal coin, instead, has two faces with different reliefs and therefore a slightly offset centre of mass, and above all it starts from a known position. Studies of the physics of coin tossing have measured a tiny tendency to land on the face it started from, around 51%.
It is a bias that changes nothing in life and that nobody manages to exploit, but it is proof that perfect randomness is a property of mathematics, not of objects. Weighted coins do exist, and the classic way to spot one is to spin it on a table instead of tossing it: there the imbalance shows immediately.
The gambler's fallacy, properly explained
After four heads in a row, the feeling that tails is «due» is almost irresistible, and wrong: the coin remembers nothing, and the fifth toss is fifty-fifty like the first. The name comes from a night at the Monte Carlo casino in 1913, when the roulette wheel came up black twenty-six times in a row and gamblers lost fortunes betting on red.
The opposite error is believing that a long run marks a «hot» coin: that too is an illusion. And it is useful to know that runs are perfectly normal: in a hundred tosses, a sequence of six identical results is almost certain, and anyone trying to make up a random sequence in their head always writes it too alternated, which is exactly how invented data is detected.
Why the law of large numbers compensates for nothing
The law says that the percentage tends to fifty per cent as tosses increase, but it does not say the differences cancel out: on the contrary, in absolute terms the gap between heads and tails tends to grow. After ten thousand tosses you can be fifty heads behind and still show a percentage of 49.75%.
In other words the balance does not arrive because the future makes up for the past, but because the past gets diluted. It is a subtle difference and it changes everything: no unlucky run will ever be «compensated», it will simply matter less and less.
When a coin is the right tool
For deciding between two equivalent options, where the time spent choosing costs more than the wrong choice: who pays for the coffee, who starts, which of two identical routes to take. It is also the quickest way to notice what you actually wanted: once the coin is in the air, you often discover you are hoping for one of the two faces, and at that point the decision is already made.
It is not the right tool when the options are not equivalent: there, handing the matter to chance is a way of not deciding, and the result has a fifty per cent chance of being the wrong one. In sport a coin is used for the toss precisely because there is nothing to weigh up, and that is its proper job.
Nearby tools
For a draw with more options there is Wheel of fortune, for numbers Random number generator and for dice Roll the dice. To split a group into teams Group generator.