How to use the coin flip
Press Flip, tap the coin, or flick it upward and let go. On a phone you can turn on Shake to flip. Want to call it first? Choose Heads or Tails above the button and the page tells you whether you called it right. A harder flick or shake sends the coin higher and spins it longer, but it changes only the show, never the result.
Rename the two sides to anything, such as Yes and No or Me and You. Choose the words people use where you live, or photograph a coin from your country and put it on the coin. Starter flips set the names and, for sports, remind you what the winner of the toss gets to choose.
How a flip is picked
The result is drawn before the coin moves. When you press Flip, the page asks your browser for a secure random number, the kind built for cryptography, and uses it to choose heads or tails. With two outcomes, the generator's range divides evenly, so no value has to be thrown out and neither side gets even a tiny edge.
Only then does the coin start moving. The page counts how many half-turns the coin makes in the air and picks a number with the right parity: an even count lands on the same face that started up, an odd count lands on the other.
heads drawn, heads up now → even number of half-turns, such as 12
The bounces and the wobble are a replay of that decision, so a hard flick or a soft one cannot change who wins.
Is a real coin flip 50/50?
Close, with one catch. In 2007 Persi Diaconis, Susan Holmes and Richard Montgomery published a physics model of a coin that is flipped and caught. It predicts that the coin lands on the side it started about 51 percent of the time. In 2023 a team led by František Bartoš collected 350,757 real flips. Coins landed on their starting side 50.8 percent of the time (95 percent credible interval 50.6 to 50.9). Heads versus tails came out at 0.500, so no side is favored. The catch matters only to someone who knows which side started up.
A coin spun on its edge on a table is different. Spun coins can be far from fair, so a toss is the better choice. This page draws the result by computer, so its flips are even.
How many flips until it looks 50/50?
Fair coins wander. For n flips, 95 percent of runs end with a share of heads within this many points of 50:
| Flips | 95 percent of runs end within |
|---|---|
| 100 | ± 9.8 points (41 to 59 heads) |
| 1,000 | ± 3.1 points |
| 10,000 | ± 1.0 point |
To land within 1 point of 50 percent in about 95 percent of runs, you need about 9,604 flips. Streaks are normal too: in 100 fair flips there is an 81 percent chance of a run of 6 or more of the same side. The Watch the odds tab shows both, drawn from real runs.
Where the numbers come from
- Random numbers: the Web Cryptography API,
Crypto.getRandomValues(). It returns cryptographically strong random values, and one call is limited to 65,536 bytes (MDN Web Docs; W3C Web Cryptography API). - Random bit generators: NIST SP 800-90A Revision 1 (June 2015). Statistical tests: NIST SP 800-22 Revision 1a.
- Same-side bias: Diaconis, Holmes and Montgomery, "Dynamical Bias in the Coin Toss," SIAM Review 49(2), 2007. Bartoš and others, "Fair coins tend to land on the same side they started," 2023 preprint.
- Super Bowl tosses: published results tables, cross-checked against two other lists. The Super Bowl is a trademark of the NFL, and this page is not affiliated with the NFL.
No laboratory has tested or certified this coin. Do not use it for gambling, lotteries or any drawing the law regulates.
Coin tosses in sports
Football (NFL): the visiting captain calls the toss, and the winner chooses to receive or kick off, or picks the goal to defend, or defers the choice to the second half (the other team then gets the other option). Soccer: the winner picks the goal to attack or the kick-off. Cricket: the winner decides to bat or field. Tennis: the winner picks serve or receive, or picks the end, and the other player chooses what is left.
Across the first 60 Super Bowls the toss landed tails 31 times and heads 29, and the team that won it won the game only 26 times. That is within what a fair coin does: the exact chance of a split at least that lopsided is about 37 percent. .
Odd history
Romans called coin tossing "heads or ship," after coins that had a head on one side and a ship on the other. Portland, Oregon, got its name in 1845 from a best-of-three toss with a copper penny. Wilbur Wright won a coin toss with his brother Orville on 14 December 1903 and crashed the first attempt. .
Tips and common mistakes
- A coin has no memory. After six heads in a row, the next flip is still 50/50.
- Ten flips will rarely split 5 and 5. Exactly 5 heads in 10 flips happens about 25 percent of the time.
- For a deciding flip between two people, agree on who calls and what each side means before the coin moves.
- A best of 3 takes 2.5 flips on average, best of 5 takes 4.1, best of 7 takes 5.8.
Questions
Is this coin flip fair?
Yes. The result is a fair random draw from your browser's secure generator, made before the coin moves. Open the Watch the odds tab to see 10,000 flips settle near 50 percent.
Does calling heads or tails help?
No. Heads and tails came out equal in the large 2023 study of real flips. The only small edge in real flips goes to someone who knows which side started up, and it does not apply to this page.
Can I flip my own coin?
Yes. Choose Use my own coin, pick a photo of each side, and move the picture until it fits. The photos stay in your browser and are not uploaded.
Are my flips saved or sent anywhere?
No, unless you press Share on Facebook or Copy the link. Those save the last result (the two names, the metal, the result and your tally) on AerialQuote for 90 days so the link can show it. Photos of your own coin are never sent, and the TikTok video is made in your browser and not uploaded.
How do I post a flip on Facebook or TikTok?
After a flip, press Share. Share on Facebook posts a link with a picture of the result. Make a video for TikTok records a 9:16 replay of your flip with the sounds, then you download it or send it to TikTok from your phone's share sheet. Both carry the address aerialquote.com/coin-flip so friends can flip their own.
Can I use it for a legal draw or a bet?
It is fine for settling a choice among friends. If the law regulates your drawing, check the rules where you live first.