Coin Flipper
Flip a coin any number of times from a seed you choose — reproducible, so the same seed always gives the same run.
The flips come from a seeded xorshift generator: your seed is hashed to start it, so a given seed always produces the same sequence.
How the coin flipper works
The flips come from a seeded xorshift generator: your seed is hashed to start it, so a given seed always produces the same sequence. That makes a draw shareable and checkable — the link carries the seed, so anyone opening it sees the same flips, which matters if you are settling something and might need to show your working later.
The longest-run figure is the interesting one. People expect runs to be short, but in 100 fair flips the longest streak is usually six or seven — a run of five heads is unremarkable, not evidence of a biased coin.
For anything where money or security depends on the outcome, use an audited random source, not a web page.
Formula: each flip is fair and independent; P(heads) = 0.5
Worked examples
| Inputs | Heads | Note |
|---|---|---|
| 100 flips | 48 | about half heads |
| Ten flips | 5 | a short run |
| A thousand flips | 475 | close to 50% |
FAQFrequently asked questions
Is this actually random?
It is pseudorandom and deliberately reproducible — the same seed always gives the same flips, so a result can be checked. That is the opposite of what you want for security.
Why does the same seed repeat?
So a draw can be shared and verified. The link carries the seed, so anyone can reproduce your run.
Is a run of five heads suspicious?
No. In 100 fair flips the longest run is typically six or seven; five is entirely ordinary.
What should I expect from 100 flips?
Fifty heads on average, give or take five — a result between 40 and 60 is unremarkable.
Can I use this to settle a bet?
For something friendly, yes, and the seed makes it auditable. For anything where money matters, use a source designed for it.
Where these figures come from
- NIST Digital Library of Mathematical Functions — reference definitions for elementary and special functions
- Wolfram MathWorld — definitions and formulas for every topic on this page
- NIST/SEMATECH e-Handbook of Statistical Methods — the statistical formulas (mean, variance, z, confidence intervals, sample size)
- National curriculum in England — Mathematics — the terms and methods taught in UK schools
Last checked: September 2026. Formulas are fixed by mathematics and do not change with tax years or regulations.