Coin flip
One tap, one honest bit of randomness, heads or tails. Fairer than a real coin and impossible to catch and turn over.
Guide
How to use it
- Call it before you tap, calling after is how arguments start.
- Tap Flip the coin and wait out the tumble, about a second.
- The tally underneath keeps score across flips for best-of series.
- Curious about fairness? Flip 100 at once and watch the split hover near 50%.
- Reset tally starts a fresh series.
Examples
Flips with something riding on them
The washing-up decider. Flip three times and the tally keeps honest score, first to two wins and the loser scrubs.
Five-a-side without a referee’s coin: one flip for ends, one for kick-off. The phone screen is visible to both captains, unlike a coin in a cupped hand.
A live statistics lesson: 100 flips typically land between 40 and 60 heads. Run it a few times, the wobble around 50% is what real randomness looks like.
Method
How it works
Each flip asks the browser’s cryptographic generator for one random bit: even means heads, odd means tails, exactly 50% each with no physical bias. Real coins, for the record, are measurably imperfect, a caught coin favours the side that started up.
The animation plays after the result is already decided, and if your system prefers reduced motion the result simply appears. The 100-flip mode draws 100 independent bits and reports the split.
FAQ
Frequently asked questions
Is this fairer than a real coin?
Slightly, yes. Studies of physical flips found about a 51% bias towards the starting face, and catching or spinning coins adds more. A random bit has no starting face.
Can I influence the outcome by timing my tap?
No. The bit is drawn from the system’s entropy pool at the moment of the tap, nothing about rhythm or timing reaches it.
Why five heads in a row?
A one-in-32 event, so it happens regularly if you flip a lot. Fair coins produce streaks, it is loaded coins that look suspiciously tidy.
Heads or tails, which should I call?
It genuinely does not matter here. With a real coin, call the face that starts upward, with this one, call whatever you like at exactly 50%.
Does the tally prove fairness?
Over many flips it should drift towards 50%, and the 100-at-once button shows it quickly. Any single session can wobble, that is expected.
Is anything sent to a server?
No. The randomness, the animation and the tally all live in your browser.
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