Flip a coin

How to flip the coin

1. Press Flip, or click the coin. It spins for about a second and lands.
2. The side facing up is your result, written under the coin: Heads or Tails.
3. Flip as often as you like. The panel beside the coin (below it, on a phone) counts this visit’s heads and tails, the total, and the current streak: how many times in a row the last side came up.
4. Press Reset to start the counts again from zero.

The counts live in the page only: they’re gone when you close or reload it.

How the flip works

Each flip takes one random bit from your browser’s secure random numbers, the kind it uses for passwords and encryption. A bit is 0 or 1, each exactly as likely: 0 is heads, 1 is tails. The result is drawn first, on your device; the spinning coin only shows it. Nothing is sent to EasiFox or anyone else.

So each side has a 50% chance, every time. The coin has no memory: after five heads, tails is still exactly 50%. Thinking a side is “due” is so common it has a name, the gambler’s fallacy. Over many flips the shares do get closer to half each, but not because tails catches up: the odd streaks just weigh less in a bigger total.

How likely is a streak?

Streaks look suspicious, but they’re normal. The chance that the next flips all land heads halves with each flip. Across a long run of flips, a streak somewhere is far more likely:

Heads in a row	From the next flip	Somewhere in 100 flips
3	1 in 8 (12.5%)	99.97%
5	1 in 32 (about 3%)	about 81%
10	1 in 1,024 (about 0.1%)	about 4%

If either side counts, the chance of a streak starting now doubles: three of the same side in a row is 1 in 4. In 100 flips, the longest run of one side is 6 or more about 81% of the time.

Best of three

One flip can feel too quick to accept. In best of three, the first to win two flips wins. It takes 2 or 3 flips, 2.5 on average, and it’s still exactly 50/50 for each person. It isn’t fairer than one flip, but people often accept it more easily. Agree on it before the first flip, not after losing it.

Settling a decision

• Say what each side means before you flip. Who takes heads, or which option wins on tails. One person can call it while the coin spins.
• Stuck between two options? Give each a side and flip. If the result disappoints you, you wanted the other one: that’s worth knowing.
• For more than two options, use Spin the wheel: each choice gets the same chance.
• To see who goes first in a game or a match, let one person call it: if the call is right, they choose.

Do real coins land 50/50?

Almost. In a 2023 study, 48 people tossed coins by hand more than 350,000 times. The coins landed on the side that faced up at the start about 51% of the time (50.8%), close to what a 2007 model of the coin toss by the statistician Persi Diaconis and two colleagues had predicted.

This coin has no starting side and no hand: every flip is a fresh 50/50.