Coin Flip
Flip 1 to 100 coins at once, see the heads/tails tally and longest streak, and check the exact odds against the binomial table below.
How one flip is decided
A coin flip is the simplest possible fair draw: one random bit, heads or tails, each with an exactly equal 50% chance. This site draws that bit with randomInt(0, 1) over crypto.getRandomValues and rejection sampling -- overkill for a range this small in terms of bias risk, but it's the same one code path every draw on the site goes through, so there's nothing coin-flip-specific to get subtly wrong.
Worked example
10 flips at a fixed illustrative seed (your real flips above use live randomness): T H H T H H T T T H -- 5 heads, 5 tails, longest streak 3.
Exact odds for 10 flips
Every possible outcome count for heads in 10 flips, computed exactly (210 = 1,024 equally likely sequences total) -- notice how wide the "close to 5" range actually is, and how a run like 8 or more heads, while uncommon, is far from impossible:
| Heads (of 10) | Ways | Probability |
|---|---|---|
| 0 | 1 / 1024 | 0.098% |
| 1 | 10 / 1024 | 0.977% |
| 2 | 45 / 1024 | 4.395% |
| 3 | 120 / 1024 | 11.719% |
| 4 | 210 / 1024 | 20.508% |
| 5 | 252 / 1024 | 24.609% |
| 6 | 210 / 1024 | 20.508% |
| 7 | 120 / 1024 | 11.719% |
| 8 | 45 / 1024 | 4.395% |
| 9 | 10 / 1024 | 0.977% |
| 10 | 1 / 1024 | 0.098% |
Frequently Asked Questions
Is this actually a fair 50/50 coin?
Yes -- every flip is one unbiased binary draw via crypto.getRandomValues and rejection sampling, mathematically identical to drawing a fair coin. There's no streak-correction, no "due for tails" adjustment, and no memory of past flips biasing the next one -- each flip is fully independent, exactly like a real coin.
If I just got 5 heads in a row, is tails 'due'?
No -- that's the gambler's fallacy. A fair coin has no memory; the 6th flip is still exactly 50/50 regardless of the last 5 results. Streaks of 5 or more happen more often than most people expect purely by chance -- see the binomial table below for exactly how often.
What counts toward the streak stat?
The longest run of consecutive flips landing the same way, across every flip you've made this session (not just the last batch) -- it resets to 1 the moment the result flips to the other side, and Clear resets it back to zero.
How is the probability table for 10 flips calculated?
By exact binomial combinatorics, not simulation: the number of ways to land exactly k heads in 10 flips is "10 choose k", and dividing by 2^10 = 1,024 total equally-likely sequences gives the exact probability -- not an approximation.
Does it work offline?
Yes, once the page has loaded -- every flip runs in your browser with no server round-trip.
Every result here is drawn live in your browser with cryptographically-secure randomness -- nothing is predetermined, saved, or replayable. See the Terms.