Coin Flip & Dice Roller
Flip coins or roll dice with cryptographically secure randomness. Runs entirely in your browser — no server, no logs.
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Frequently asked questions
Is this a fair / random coin flip or dice roll?
Yes. This tool uses the Web Crypto API (crypto.getRandomValues) — the same source browsers use to generate encryption keys. It draws entropy from your operating system's secure random pool, not a predictable algorithm. Each flip or roll is statistically independent.
What is a D20 dice?
A D20 is a 20-sided die used in tabletop RPGs like Dungeons & Dragons. The 'D' stands for die; the number after it is the number of faces. Other common types: D4 (pyramid), D6 (standard cube), D8 (octahedron), D10, D12, and D100 (percentile, used by rolling two D10s).
What is the probability of getting heads?
Exactly 50% for a fair coin — each flip is independent so prior flips never affect the next one. With 2 coins: both heads = 25%, one of each = 50%, both tails = 25%. With n coins, the probability of exactly k heads follows the binomial distribution: C(n,k) x 0.5^n.