Coin Flip Simulator
Flip a virtual coin with a satisfying animation. Run single flips or flip up to 100 coins at once. Track heads/tails statistics and streaks over time.
Flip Multiple Coins at Once
Statistics
Probability Theory & the Law of Large Numbers
A fair coin has a 50% probability of landing heads and 50% tails on any single flip. However, in small samples you will often see streaks and imbalances — that is completely normal.
The Law of Large Numbers states that as the number of flips increases, the observed ratio of heads to tails will converge toward the theoretical 50/50. Try flipping 100 coins multiple times to see this in action — the ratio will get closer and closer to 50%.
Frequently Asked Questions
A theoretical fair coin is exactly 50/50. In reality, physical coins have very slight manufacturing imperfections that can bias results by a fraction of a percent. Research by Diaconis et al. also found that a coin is slightly more likely to land on the same face it started on (~51%), due to the physics of the flip.
A streak is a consecutive sequence of the same result. In 10 coin flips, there is about a 50% chance of seeing a streak of 4 or more. In 100 flips, a streak of 7 is very likely. Long streaks feel improbable but are a normal feature of random sequences.
On average, you need about 2^11 - 2 = 2,046 flips to see 10 consecutive heads. The expected waiting time for a streak of n is (2^(n+1)) - 2 flips for a fair coin.
Yes. The simulator uses Math.random() which is a well-seeded pseudorandom generator in your browser — perfectly suitable for games, decision-making, and probability demonstrations. For security-critical randomness, use a cryptographic source.
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