Is a coin flip really 50/50?
How randomness makes a coin toss fair, why streaks happen, and what the gambler's fallacy gets wrong about heads and tails.
What fair actually means
A fair coin gives heads and tails an equal 50 percent chance on every single throw. Fairness is a property of one flip, not of a batch. It does not promise that ten flips split exactly five and five, only that over the long run the proportion of heads settles near one half. This tool models that by treating any random value below 0.5 as heads and the rest as tails, which splits the range evenly.
Why streaks are normal
Runs of the same side are expected, not suspicious. In a session of ten flips, seeing four or more of one side in a row is common. Because each toss is independent, the coin has no memory of what came before, so a streak carries no pressure to reverse. The Session tally makes this concrete: short runs can swing the percentage far from 50, and it is only after many flips that the split tightens toward even.
The gambler's fallacy
The gambler's fallacy is the belief that a run of heads makes tails due. It feels intuitive but it is false for independent events. After five heads, the next flip is still 50 percent heads and 50 percent tails. The math that pulls long-run results toward 50 percent works by adding more flips, not by correcting past ones. No amount of history changes the odds of the very next toss.
When you need stronger randomness
For a game night or settling who buys coffee, the browser generator behind this flipper is more than fair enough. For security work such as generating keys or tokens you would want a cryptographic random source instead, because ordinary generators are predictable to an attacker who knows their internal state. For casual fairness, though, an unbiased even split is exactly what you want.