Is a coin flip really fifty-fifty?
Real coins land the way they started slightly more often than half the time. What the research found, and how a fair online coin flip works.
By Suraj Kumar4 min read
We flip coins because they feel perfectly fair. They are close, but not exact: real coins have a small, measurable lean. An online coin can be fairer than a real one.
Real coins lean to the side they started on.
A 2007 analysis of how coins spin in the air predicted that a flipped coin lands the same way up as it started about 51% of the time. In 2023, a team recorded 350,757 real flips by 48 people and found 50.8%, with some people's flips leaning more than others.
An online coin with no lean.
On KeepSimp each side comes from your browser's cryptographic generator with exactly the same chance, so there is no starting side to favour. The flip on screen is an animation of a result already drawn.
Streaks are normal.
Flip a hundred coins and you will usually see a run of six or seven of the same side somewhere. That is chance, not a pattern, and the next flip is still even. The page shows the longest run of heads and of tails, so you can see how long streaks get.
To settle something properly, play best of three or five under More options.
Further reading
Topics: flip a coin · coin flip · is a coin flip 50 50 · heads or tails · coin toss odds · coin flip simulator
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