Coin Flip
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Flip a coin to see your results here.
Result
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Total Flips0
Heads0 (0%)
Tails0 (0%)
Current Streak
Longest Streak
Last 30 flips
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The Probability of Coin Flips
A fair coin has exactly 50% probability for each side on every individual flip. Importantly, each flip is independent — previous results do not influence future ones. This is the gambler's fallacy: getting 10 heads in a row does not make tails "due" on the next flip.
Over a large number of flips, the law of large numbers ensures the ratio converges toward 50/50. Try flipping 10,000 coins to see this in action.
Independence
Each flip is a fresh 50/50 event. Getting heads 10 times does not increase the probability of tails on flip 11.
Streak Probability
A streak of 10 heads has probability (0.5)^10 = 0.098%. In 1,000 flips, you expect at least one 10-head streak.
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Frequently Asked Questions
Is this coin flip truly random?+
Yes. Each flip uses Math.random() which generates a pseudorandom number between 0 and 1. Numbers below 0.5 = heads, above = tails. Each call is independent and produces a 50/50 result over large samples.
What is the gambler's fallacy?+
The belief that past outcomes affect future independent events. After 10 heads in a row, the probability of tails on the next flip is still exactly 50%. Streaks feel meaningful to humans but are expected and normal in random sequences.
How long does the longest possible heads streak get?+
Mathematically there is no limit, but long streaks become increasingly rare. The expected length of the longest streak in N flips is approximately log2(N). In 1,000 flips, expect a streak of about 10. In 1,000,000 flips, about 20.
Can I use this to settle a dispute?+
Absolutely. A virtual coin flip is as fair as a physical one for decision-making purposes. Both parties must agree before the flip that they will honor the result.
Why does my coin show emoji?+
The coin displays a medal emoji as a playful representation. Heads and tails are distinguished by the animation result and the text display above.
What is the probability of exactly 5 heads in 10 flips?+
Using the binomial formula: C(10,5) x (0.5)^10 = 252/1024 = approximately 24.6%. The most likely single outcome in 10 flips is 5 heads, but it still happens less than 25% of the time.
What if I want to flip a weighted coin?+
Use the "Which Side Wins" selector to force a specific outcome every time — useful for testing. There is no partial weighting (e.g., 60/40) in this tool; for that, use the random number generator set to 1-100 with a threshold.
How many flips to prove a coin is fair?+
Statistically, about 10,000 flips gives enough data to detect a bias of a few percent with high confidence. Small samples look wildly unfair by chance even for perfectly fair coins.
What does current streak mean?+
The current streak counts consecutive identical results (e.g., 5 heads in a row). When the result changes the streak resets. The longest streak tracks the best run in your entire session.
Can I use this for a Magic 8-Ball style decision?+
Yes! Assign heads = yes and tails = no. For more nuanced decisions with multiple options, use the Name Picker Wheel or Random Number Generator instead.