Coin flip
Press Flip for heads or tails, or flip a batch at once to see how a fair coin behaves over many tosses.
Free · no signup Runs in your browser
How do I flip a coin online?
Press Flip a coin and the page shows heads or tails, each with a 50% chance. To see how a fair coin behaves over many tosses, set a number and press Flip many. The tally keeps a running count of heads and tails on the page. Each flip uses one secure random bit from your browser, so the result cannot be predicted or influenced.
Is a virtual coin fair?
A real coin is very close to fair, with a tiny tendency to land on the side it started from if it is flipped with little spin. A virtual coin has no such bias: here each flip is one random bit taken from the browser's secure generator, so heads and tails are exactly equally likely and every flip is independent of the ones before it.
Independence is what surprises people. After five heads in a row, the next flip is still 50/50, because the coin has no memory. Streaks are a normal feature of randomness: in 100 flips, a run of six or seven of the same side is more likely than not. The tally above shows this when you flip a hundred or a thousand times: the percentage of heads settles near 50% but does not stay there from one flip to the next.
It runs in your browser. Nothing is sent or stored, and there is no sign-up.
Using a coin flip to decide
A coin flip is a good way to break a tie when both options are acceptable, and it has a hidden benefit: how you feel while the coin is in the air often shows which side you wanted. For a decision with more than two options use the random name picker or the dice roller. For anything with real stakes, a coin is a way to settle a tie, not to avoid thinking.
When to use it
- Settling a tie or choosing who goes first
- Showing students how probability behaves over many trials
- Making a quick decision between two equal options
- Testing a simulation against the 50% expectation
Mistakes it helps you avoid
- Believing the next flip is 'due' after a run of one side (the gambler's fallacy).
- Expecting exactly 50% heads in a short run.
- Re-flipping until you get the answer you wanted.
- Using a biased method such as a flip with a tiny spin.
The formula
How the answer is worked out.
1. Take one random byte from the browser's secure generator.2. Look at its lowest bit: 1 is heads, 0 is tails.3. Add the result to the running tally.4. Heads so far = heads ÷ total flips × 100
Each flip is a Bernoulli trial with probability 0.5. The expected share of heads is 50%, and for n flips the typical wobble around it is about 50% ± 50%/√n, so a thousand flips usually lands between 48% and 52%.
Example: 100 flips
You flip a coin 100 times.
- Expected50 heads and 50 tails
- Typical resultbetween about 45 and 55 heads
For example: 53 heads, 47 tails (53% heads)
A longest streak of six or seven in 100 flips is normal.
Terms on this page
- Gambler's fallacy
- The mistaken belief that a result is 'due' after a streak of the opposite one.
- Bernoulli trial
- An experiment with two outcomes, such as a coin flip.
Common questions
Is the coin flip fair?
Yes. Each flip is one secure random bit, so heads and tails are equally likely.
If I get five heads in a row, is tails more likely next?
No. Each flip is independent.
How many flips can I do at once?
Up to 10,000.
Is my tally saved?
No. It exists only on this page until you reset or leave.
Can I use it to make a big decision?
It can settle a tie. Your reaction to the result can also tell you what you wanted.
Is anything I enter sent to a server?
No. The calculation happens in your browser and nothing you type leaves your device.
Where these numbers come from
- MDN Web Docs — Crypto.getRandomValues() The browser's cryptographically strong random number source used by these tools.
- Wikipedia — Bernoulli trial Why a fair coin gives heads half the time in the long run, but not in every short run.
Last verified 2026-10-25 The method on this page is checked against the sources above at least once a year. Spotted something out of date? Tell us and we will fix it.
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