Math.random() for a statistically fair 50/50 resultA fair coin flip is a classic source of binary randomness. This simulator uses Math.random() — JavaScript's cryptographically seeded pseudo-random number generator in modern browsers — to produce statistically fair 50/50 results. Use it to make quick decisions, settle disputes, or run probability experiments.
Math.random() in modern browsers (Chrome, Firefox, Safari) is implemented with xorshift128+ or a similar CSPRNG-seeded PRNG, making it statistically excellent for simulation purposes. Over large numbers of flips, the heads/tails ratio converges to 50%/50% as expected by the law of large numbers. If you need cryptographic randomness (for security applications), use crypto.getRandomValues() instead.
It uses JavaScript's Math.random(), which is seeded from system entropy and is practically indistinguishable from random for non-security purposes. For cryptographic randomness, the tool is not the right choice.
Runs are expected in random sequences. The probability of 5 heads in a row is (0.5)^5 = 3.1% — rare but not unusual. Over hundreds of flips, the ratio will converge to near 50:50.
Yes. The statistics panel tracks cumulative results, making it useful for demonstrating the law of large numbers: the empirical frequency converges to the theoretical probability as the number of trials increases.
(0.5)^10 ≈ 0.097% — about 1 in 1,024. This will happen roughly once every 1,000 sequences of 10 flips on average.
See also the Dice Roller for D4–D20 random outcomes and the Random Number Generator.