Coin Flip & Dice Roller

Overview

Cryptographically random coin flips and dice rolls for games, decisions and settling disputes. The coin section keeps a short history of flips; the dice section rolls one to ten dice of any standard shape from d4 to d100 and shows the individual results plus their sum. Everything is generated on your device with the browser's cryptographic random source.

How It Works

For a coin, press Flip a coin and read HEADS or TAILS; the last ten results stay listed above the button so you can spot streaks. For dice, set the number of dice (1 to 10) and pick a die size from the dropdown - d4, d6, d8, d10, d12, d20 or d100 - then press Roll. Each die's value appears in its own square with the total underneath. There is nothing to configure beyond that: no sign-up, no loading spinner, and no randomness faked with the ordinary Math.random function.

Step-by-Step Usage Guide

1. Press Flip a coin for a decision; the last ten flips remain visible.
2. Set how many dice you want, between 1 and 10.
3. Choose the die size from d4 to d100.
4. Press Roll and read the individual results and the sum.

Technical Specifications & Standards

Both generators draw from crypto.getRandomValues, the Web Crypto API's cryptographically secure random source, rather than Math.random, which is seeded predictably enough to be unsuitable for anything fairness-sensitive. The coin takes one random byte and tests whether it is even, giving a 50/50 split with a bias of at most about 0.4 percent from the modulo of a 256-value byte. Dice take one 32-bit random integer per die and apply modulo sides plus one; because 2^32 divided by any die size up to 100 leaves a small remainder, there is a tiny modulo bias, bounded and far below what a physical die exhibits. The result history for coins is capped at ten entries in memory and is never persisted. No rolls are sent to a server or logged, which makes the tool usable for games where you would not trust a stranger's website - though it also means results cannot be audited after the fact.

Targeted Use Cases

• Board game nights where the physical dice have gone missing.
• Settling a who-goes-first decision without argument about fairness.
• Tabletop RPG sessions needing several d20 or d100 rolls at once.
• Randomly assigning a small binary choice, like which of two tasks to start.

Notes & Gotchas

• For RPGs, roll all dice in one press so the sum is computed for you.
• Remember a fair coin still produces streaks; five heads in a row is not a malfunction.
• Use d6 for anything where players expect familiar odds.
• Reload the page to clear the flip history before a new game.

Frequently Asked Questions