Coin Flip

About this tool

This coin flip uses your browser's random number generator for a fair, independent 50/50 result on every flip. Flip once for a quick decision, or flip hundreds of times at once to see how the heads/tails split evens out over a larger sample.

How to use the Coin Flip

1. Set the number of flips — leave it at 1 for a single flip.
2. Tap Flip to get your result.
3. Check the tally if you ran multiple flips at once.

Common use cases

• Making a quick 50/50 decision when you can't decide between two options
• Settling who goes first in a game
• Running a batch of flips to see the heads/tails distribution over a larger sample size

Why flips can "streak" even though it's fair

Getting several heads in a row can feel suspicious, but it's a normal and expected outcome of true randomness — each flip is independent, with no memory of what came before, so the coin is exactly as likely to land heads after five heads in a row as after five tails. Over a small number of flips (say, 10), it's common to see a 6-4 or even 7-3 split purely by chance. The 50/50 split becomes more reliable the more flips you run — that's why the "flip many at once" option is useful for seeing the law of large numbers in action rather than judging fairness from just one or two flips.

Things to watch out for

This is a software random number generator, not a physical coin — it's suitable for games, casual decisions, and everyday fairness, but it's not built for cryptographic or high-stakes gambling use, where a different class of randomness (and often independent auditing) is expected.

Using a coin flip to decide

A fair coin lands heads or tails with a 50% chance each, so it is a neutral way to break a tie. One trick: if you feel disappointed by the result, that tells you which option you actually wanted. For best-of-three or best-of-five decisions, flip repeatedly and count wins. Flips in this tool are independent, so five heads in a row makes the next flip no more likely to be tails.

How often a fair coin really splits evenly

Every flip here is independent, with a 1 in 2 chance of heads. Flip it n times and the chance of getting exactly k heads is the binomial formula: C(n, k) ÷ 2 to the power n, where C(n, k) is the number of ways to choose which k flips are heads. The results are less tidy than most people expect:

So in 10 flips, a perfect 5-5 split happens only about a quarter of the time. In 100 flips, an exact 50-50 result happens under 8% of the time, even though the share of heads usually lands close to half. A run of five or more heads or tails in a row turns up in almost half of all 20-flip sessions. Seeing a long streak is not evidence that the coin is broken.

Streaks of the same side: the math

The chance that the next k specific flips all land heads is (1/2) to the power k: 1 in 8 for three in a row, 1 in 32 for five and 1 in 1,024 for ten. That sounds rare, but in a long session there are many places a streak can start, which is why the table above shows streaks being common. The table values were computed exactly by counting every possible sequence.

Using a coin flip fairly

• Call it before you flip. Decide who has heads before tapping Flip, so no one can reinterpret the result.
• Best of three doesn't change the odds. With a fair coin each side still wins a best-of-three with probability 1/2. It only makes the decision feel more considered.
• More than two options? A coin can only split two ways evenly. For three or more choices use the Random Number Generator and assign each option a number.
• Batch mode is capped at 1,000 flips per tap. Tap again for more and add the tallies together.