Coin Flip
Flip one coin or ten thousand. Heads and tails counts, percentages, a keyboard shortcut and an animation you can switch off.
Selections are generated locally in your browser using the Web Crypto API when available. The result is chosen before the animation starts, so how the animation looks can never change what is picked.
Loading the coin flip…
What is the Coin Flip?
A virtual coin with an honest 50/50 outcome. Single flips get a short animation and a large result; bulk flips skip the animation and produce the totals immediately, which makes the tool useful for probability lessons as well as for settling who goes first.
The running totals show heads, tails and percentages for the session, plus the last sixty flips as a strip — a good way to demonstrate that streaks are normal rather than suspicious.
How to use it
- Press “Flip the coin”, or just press F or the space bar.
- For many flips at once, enter a number in “Flip several at once” and press “Flip many”.
- Watch the session totals update, and reset them whenever you like.
- Copy or download the flip log if you need a record.
How the random selection works
Every flip draws a single integer, 0 or 1, from crypto.getRandomValues() with rejection sampling. The coin animation starts only after the result has been decided, and bulk flips are drawn one at a time so each is fully independent — the tool never generates “45 heads out of 100” as a number and then fabricates a sequence to match.
The full algorithm — including the rejection-sampling step and the wheel stop-angle calculation — is written out on the methodology page.
Practical examples
- Deciding who kicks off, serves or goes first.
- Running a 1,000-flip experiment to show a class how proportions converge.
- Making a genuinely 50/50 choice when both options are equally good.
- Demonstrating that a run of six heads is unremarkable in a long sequence.
Available options
- Single flip with an animation, or bulk flips without.
- Up to 10,000 flips in one action.
- Heads/tails counts and percentages for the session.
- Recent-flip strip, CSV export and reset.
- Keyboard shortcut, sound toggle and animation toggle.
Privacy
Coin flips involve no personal data at all. Everything you type stays in this browser tab. There is no account, no upload step and no server-side copy of your list: the draw runs in JavaScript on your own device. Nothing is written to browser storage unless you explicitly save a list or tick the option to keep your draw history, and both can be cleared at any time from the privacy page.
Full details are in the privacy policy, which also has a button that deletes everything this site has stored in your browser.
Fairness and limitations
Each flip is an independent 50/50 event. That means the coin has no memory: after five heads, the next flip is still exactly 50/50, and a session that ends 54/46 after 100 flips is entirely ordinary. If you flip enough times the proportion will converge towards half, but individual runs of the same side will keep happening — that is what randomness looks like, and it is the reason this tool shows the recent-flip strip.
Frequently asked questions
Is it really fair?
Yes. Each flip is one uniformly drawn bit, and the animation is decided after the result. Over large numbers of flips you will see the proportion settle near 50%.
I got eight tails in a row. Is something wrong?
No. An eight-run happens roughly once every 256 sequences of eight, so in a few hundred flips it is expected. Past flips never influence the next one.
Why does “flip many” skip the animation?
Because animating a thousand flips would take twenty minutes. Each flip is still drawn independently — only the display is condensed.
Is there a keyboard shortcut?
Yes: F or the space bar, as long as you are not typing in a field.