How It Works

The Short Version

1. Your browser's secure random tool picks the winner.
2. The wheel is animated so it slows down and stops on that winner.
3. The sound and motion are just the show. They do not change the result.

Most spinners work the other way. They spin first, and wherever the wheel stops is the answer. That makes the result depend on timing, speed and small differences between devices. We pick first, then animate.

Step 1: The Winner Is Chosen

Your browser has a built-in source of unpredictable numbers, called crypto.getRandomValues. Browsers use the same kind of source for security. We use it to pick a number, and that number selects the winning entry.

There is one detail that matters. Say you have 7 entries. A computer cannot split its random numbers into 7 perfectly equal groups, because 7 does not divide evenly into the size of a computer number. A common shortcut, "take the remainder", makes a few entries very slightly more likely than the rest. The gap is tiny, but it is real.

We use a method called rejection sampling instead. If a draw falls in the uneven leftover, we throw it away and draw again. Every entry ends up with exactly the same chance.

Step 2: The Spin

When the winner is known, the animation works backward. It works out how far the wheel must turn to stop on that winner, and plays a smooth slowdown that ends there.

The ticking sounds are made on your device, using your browser's built in audio tools. They follow the speed of the wheel. No audio files are downloaded.

Is It Really Random?

Yes, in every way that matters for a wheel. There are two kinds of random in computing.

• Pseudo-random. A formula makes numbers that look random but come from a starting value called a seed. It is fast and fine for games. But if someone knew the seed, they could predict the next number.
• Cryptographically secure. The numbers come from sources your device collects from hardware and system activity. They are built so nobody can predict the next one. This is what crypto.getRandomValues uses.

Our wheels use the second kind.

Can the Result Be Predicted or Rigged?

Not by us, and not by you. The result is not stored anywhere before you press spin. No setting changes the odds of one slice.

If you want different odds, put an entry on more slices yourself. The wheel stays fair, but your list changes the chances. The free wheels have no weight setting.

Why Do I Sometimes Get the Same Result Twice?

Each spin is separate. The wheel has no memory, so a repeat is as likely as any other result. With 10 entries, the chance of the same winner twice in a row is 10%. That is how randomness works. It is not a fault.

Does It Look for Patterns?

Random results often look like they have patterns. Streaks, like three of the same result in a row, happen more often than people expect. If you spin a 6 slice wheel 20 times, a streak of 2 or more is almost certain. People are good at spotting patterns and bad at guessing how often chance makes them.