Coin Flip

How does the tool decide heads or tails?

For each flip it evaluates Math.random() < 0.5 in your browser: below 0.5 is Heads, otherwise Tails. Math.random is a general-purpose pseudo-random generator, not a cryptographic one, and nothing about previous flips affects the next. It is fine for settling who goes first; do not rely on it for anything where someone could profit from predicting the outcome.

What is the maximum number of flips?

The count is clamped between 1 and 1,000. Entering 0, a negative number or text gives a single flip, and entering 5,000 silently runs 1,000. The sequence is printed in full as a comma-separated list, so a 1,000-flip run produces a long line; the Heads and Tails counts underneath are the quick summary.

Why do I get streaks like Heads, Heads, Heads, Heads?

Real random sequences contain streaks far more often than people expect. In a run of 10 fair flips, the chance of at least one stretch of four or more identical results is about 46%. A flip that follows three heads still has exactly a 50% chance of heads, because each flip is independent. Seeing a streak is not evidence that the generator is stuck.

Does the page remember earlier results or keep a running total?

No. Each click is a fresh calculation and the previous set is replaced. The percentages shown cover only the flips in the current run. If you want a long-run tally, raise the number of flips in one go, or write down the counts yourself.

Can it flip a coin for more than two options?

No, the output is only Heads or Tails with equal probability. For three or more choices use a dice roller or assign options to numbers yourself. To pick between two named options, decide beforehand which one is Heads and treat the first result as final.

Is a real coin also 50/50?

Close, but not exactly. A study of hand-flipped coins by Diaconis, Holmes and Montgomery found a small bias towards the side that starts facing up, around 51%. A virtual coin has no starting side, so the code uses an exact 50% split by design.

Why does 100 flips rarely land on exactly 50 heads?

Exactly 50 heads in 100 fair flips happens only about 8% of the time. About seven runs in ten land between 45 and 55 heads, so anything in that band is normal. The proportion converges on 50% as flips increase, but the raw difference between heads and tails tends to grow slowly rather than shrink.