How to Flip a Coin

Step by step

Here is how to flip a coin the fair way, in five steps.

1. Make a loose fist with your thumb tucked under your curled index finger, and rest the coin flat on top of that finger. 2. Agree who calls, and keep the starting side hidden if you can. 3. Flick your thumb up firmly so the coin rises and turns over many times in the air. 4. The caller says heads or tails while the coin is still in the air. 5. Catch it in your palm, or let it land on a soft, flat surface, then read the side facing up.

If the coin hits something on the way down or rolls away, just flip again.

Call it before or during the flip

Make the call before the coin lands, ideally while it is in the air. Calling during the flip means nobody can wait to see which way it is going, and the person tossing cannot react to the call. If you call before the flip, the tosser knows your call and, in theory, could see which side starts up. With a same side effect of 50.8% that edge is tiny, but hiding the starting side removes it completely. Agree on the rules out loud first: who calls, whether the coin is caught or allowed to land, and what happens if it falls on the floor. That avoids the classic argument afterwards.

Catch or let it land?

Catching a coin and letting it land on a soft surface are both fair, as long as you agree before the toss. Catching the coin in your palm is quick and keeps it off the floor. Letting it land on a soft, flat surface like a bed, a rug or a towel is also fine, because the coin stops where it falls instead of rolling away or ending up on its edge. What you should avoid is a hard table where the coin bounces and then spins, since spinning lets the shape of the rim and the weight of each face play a part. Whichever you pick, say it out loud first, and redo any toss that hits a wall or a person on the way down.

Don't spin it on a table

Spinning a coin on a table is far less fair than flipping it. A spinning coin slows down gradually and tips over toward one side, so small differences in the rim and in each face's design can push the result one way. The Wikipedia article on coin flipping says spun coins are much more likely to be biased than flipped ones, and Gelman and Nolan point to spinning as the case where a coin really can lean. A flipped coin spends its time turning in the air, where those differences barely matter. Spinning is fun to watch, but when a decision depends on it, flip the coin instead.

How to make a toss truly fair (hide starting side, let someone else flip)

To make a coin toss as fair as possible, hide the starting side and let someone who is not calling do the flip. The only known physical bias in a real flip is that the coin lands the same way up it started 50.8% of the time (Bartoš et al. 2023). If the caller cannot see the starting side, that small edge cannot help anyone. Letting a neutral person toss, the way a referee does before a match, removes any suspicion of a well trained thumb. Then catch the coin or let it land on a soft surface, and never spin it. For full proof, use a digital coin whose result can be checked afterwards.

Flip a coin over text, in a chat or online

To flip a coin over text, use an online coin flip that both of you can trust, rather than one person's word. Flipping a real coin and typing heads into a chat only works if the other person believes you. With FlipACoin you can flip right in the browser, or, in the app, create a private room and send your friend the 6 character code or link on WhatsApp, iMessage or any other chat. You both call and watch the same flip live. Each result comes with a hash published before the flip, so either of you can confirm it on the Verify page afterwards.

Flip, spin or digital