Heads or tails
The oldest two-option decider there is. Call it out loud, flip, and let the coin carry the blame.
Guide
How to use it
- Agree what heads means and what tails means before anyone flips.
- One person calls, out loud, mid-air is traditional but before the tap is fine.
- Tap to flip. The face lands in about a second and the tally records it.
- Series are fairer than single flips for grudges: first to three, tally on screen.
Examples
The etiquette, settled
Convention says the person who did not suggest the flip makes the call. Nobody gets to both propose the game and pick the side.
For decisions with feelings attached, a series feels fairer than sudden death, and the on-screen tally means nobody is keeping score in their head, generously.
Real-world flips get voided by table edges, drains and dogs. This one cannot roll under the sofa, every flip counts.
Method
How it works
Each flip draws one bit from the browser’s cryptographic generator: even is heads, odd is tails, a perfect 50% with no starting-face bias, which physical coins measurably have.
The phrase itself goes back to Roman "navia aut caput", ship or head, the two-sided coin call has been settling disputes for over two thousand years. This page just removes the sleight of hand.
FAQ
Frequently asked questions
Which side should I call?
Here, either, both are exactly 50%. Superstition favours heads and most people call it, which is precisely why it does not matter.
Is heads more likely on real coins?
A famous study found caught coins land the same face they started about 51% of the time. The bias belongs to the flip, not the face, and digital flips have neither.
What if it lands on its edge?
It cannot, one bit has two values. The 1-in-6,000 edge landing of a real 5p is the only feature this page lacks.
Can we do best-of series?
Yes, the tally underneath counts heads and tails across flips, first to the agreed number wins. Reset it between disputes.
Is the call binding?
That is between you and the other party. The coin’s part of the contract is honest, the enforcement clause is yours.
Why do people trust coin flips at all?
Because both sides can see the mechanism and neither can steer it. This version keeps both properties, the randomness is cryptographic and the tally is public.
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