Coin Flip

Flip 100 coins and you will usually land within a few of 50 heads — but exactly 50/50 happens only about 8% of the time, which is why single flips feel streaky and fair at once.

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How it works

The oldest decision machine in the world, minus the coin, the floor, and the argument about whether it landed on a crack. One flip settles the question; a hundred flips show you what fairness actually looks like — near-even splits with honest wobble, and streaks that mean nothing at all.

Calling it in the air remains your responsibility.

The method

Each flip is one bit drawn from crypto.getRandomValues — heads on 0, tails on 1 — so every flip is independent and exactly 50/50. Batch percentages are counts divided by flips, nothing fancier.

Check important dates twice. Every result here is worked out from the values you enter and the calendar, clock and counting conventions described on the page. Date and time answers can depend on time zones and daylight-saving rules, and counting tools follow the definitions printed with them. For deadlines, filings, payroll or anything with money attached, confirm the figure against an authoritative source.

Frequently asked questions

Is it really 50/50?

Yes — one unbiased cryptographic bit per flip. Real coins have tiny biases from their faces and the flipper's technique; this one has neither.

Why did I get five heads in a row?

Because in 100 flips, a run of five heads somewhere is not just possible but likely. Streaks are what randomness looks like; perfect alternation would be the suspicious result.

Can a coin flip make a good decision?

It settles ties fairly, and it has a second use: the moment the coin is in the air, you often discover which result you were hoping for. That discovery is the decision.

Embed this tool

Put this tool on your own site for free — copy the code below. It runs entirely in the visitor's browser, like it does here.

<iframe src="https://calcwhen.com/embed/coin-flip/" width="100%" height="520" style="border:1px solid #d9d5f2;border-radius:12px" loading="lazy" title="Coin Flip — CalcWhen"></iframe>

Tool by CalcWhen — please keep the credit link so others can find the original.