Interpret a short streak
- Input or situation
- Five flips all land heads.
- Result
- That particular sequence has probability 1 in 32.
Multiply five independent one-half probabilities: (1/2)⁵. The next flip still has a one-half probability of heads.
Random
Coin flip — heads or tails, a true 50/50
Flip a coin — or a hundred at once — with a truly 50/50 cryptographic flip, a running tally, and the heads percentage as it converges.
Runs in your browser — your input is not uploaded to ToolsNow.
Flip to get heads or tails.
The result is generated locally in your browser.
Each flip is an independent 50/50 draw from the browser's cryptographic generator. The running tally is there to watch the law of large numbers do its thing: short runs of several heads in a row are completely normal, and the percentage only settles near 50% over many flips. Past flips never influence the next one — the gambler's fallacy is believing otherwise.
How to use
- Flip. One coin for a decision, many for an experiment.
- Read the result. Heads or tails, with each coin shown.
- Watch the tally. The running percentage drifts toward 50% as flips accumulate.
Questions
Is this really 50/50?
Exactly 50/50, from the browser’s cryptographic generator — which is more than can be said for a physical coin: studies of real coin flips find the side facing up at launch lands up about 51% of the time, because of precession in the toss.
I got five heads in a row. Is it broken?
No — runs are what genuine randomness looks like. Five heads in a row has a 1-in-32 chance on any five flips, so it happens regularly. Each flip is independent: after five heads, the next flip is still exactly 50/50. Feeling that tails is now “due” is the gambler’s fallacy.
Why does the percentage settle near 50% but the counts drift apart?
The law of large numbers guarantees the ratio converges, not the difference. After 10,000 flips a gap of 100 between heads and tails is normal — that is a 1% difference in share — and the absolute gap typically grows with the square root of the number of flips even as the percentage tightens.
Can I use this to decide something important?
A coin flip is a time-honoured tie-breaker because it is incorruptible and instant. There is also a real psychological trick in it: if the result disappoints you, you have just learned what you actually wanted — at the cost of one flip.
Examples and checks
Use a single flip for an informal choice or batches to explore probability. The running totals describe the flips already made; they cannot predict the next result.
Compare a batch
- Input or situation
- 100 independent flips
- Result
- 50 heads is the expected count, not a guaranteed count.
Repeated batches vary. A result above or below 50 is expected and does not by itself show that the generator is biased.
Before you use the result
- A browser-generated result is not an independently auditable draw. Do not use it as proof that a regulated or prize-bearing competition was conducted fairly.
- Agree on what heads and tails mean before flipping, and avoid repeating the flip merely to get a preferred answer.
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