About Coin Flip
Coin Flip returns heads or tails, once or many times. A single flip answers a binary decision; a run of flips gives you a sample you can compare against an expectation, which is the usual reason to generate more than one.
Each flip is independent of every other, which is the property that makes the results worth looking at: a run of ten does not become more likely to end in tails because the first nine were heads. That independence is exactly what people expect from a fair coin and is the opposite of what many people intuitively assume.
The results are produced by the ordinary pseudo-random generator in the browser rather than the cryptographic one, so they are unpredictable to a person and not unpredictable to a determined analysis of the generator sequence. For deciding who pays for lunch that makes no difference; for anything with an incentive to be gamed, it does.
How to use Coin Flip
- 1 Set how many flips you want, up to a hundred.
- 2 Read the results, one per line, in the order they were produced.
- 3 Count the heads if you want to see how the run came out.
Frequently asked questions
Are the flips truly 50/50?
Each flip is an independent draw with equal probability for the two outcomes, which is what a fair coin means. A short run can still look very lopsided — ten flips producing eight heads is unremarkable and not evidence of bias.
Does a run of heads make tails more likely next?
No. Each flip is independent, so the previous results carry no information about the next one. The intuition that a correction is due is a well-documented mistake rather than a property of the process.
Can I use this for something that needs to be provably fair?
No. The randomness comes from the ordinary pseudo-random generator in your browser, which is not designed to be unpredictable to an observer who knows the sequence. Things that must be provably fair need a commit-and-reveal scheme or a public source of entropy.
Free, online, and private
Free to use
Coin Flip is completely free. There is no account to create, no login, and no hidden charge or usage limit.
Runs online in your browser
It is a free online tool that runs entirely in your browser. Nothing to download or install — open the page and start using it right away.
Your data stays private
All processing happens locally on your device. Your input is never uploaded, stored, or tracked, so it never leaves your browser.
How Coin Flip behaves in detail
These are the specifics of this implementation — the exact ranges, defaults and fixed settings you are working with.
| Parameter | Value |
|---|---|
| Outcome per flip | one of exactly two strings — Heads or Tails |
| Batch output | 1 to 100 lines, default 10, one result per line |
| Entropy source | a single Math.random() draw compared against 0.5 |
| Totals reported | none — the output is the bare list of results |
Compiled from the implementation of this tool and checked against it by itoolnet.
What Coin Flip does not do
Knowing the edges of a tool saves more time than another list of its features. These are the cases where it will not do what you might expect.
- The flip is one Math.random() draw compared with 0.5, and Math.random() is not a cryptographic source, so the sequence cannot be shown to be unbiased to anyone who has to trust the result.
- No tally is produced beside the list: ten flips print ten lines with no count of how many came up Heads, and nothing is carried between batches, so ten Heads in a row is a possible result that nothing in the tool will flag.
- The two outcomes are hard-coded to the words Heads and Tails. There is no way to relabel them for a custom coin, and no option to flip a coin whose two sides are not equally likely.
Tested and documented by itoolnet, the team that builds and maintains this site.