Making Fair Decisions with a Roulette Wheel

A roulette wheel divides a disc into equal-sized slices — one per item — spins it hard, and takes whichever slice the pointer lands on as the result. Since every slice has the same angle, every item has the same odds of being picked.

Why the odds are equal

With N items, each slice spans 360 degrees divided by N. The wheel spins around enough times that where it stops is unpredictable, and the odds of the pointer landing on a given slice are proportional to that slice's angle. Since every angle is equal, so are the odds.

When a roulette wheel works best

• When you want all the candidates laid out visually so everyone can see what's up for grabs
• When a group wants the shared fun of watching the screen together and waiting for the result
• When you need to make a quick, low-stakes decision, like picking lunch or a weekend activity

Tips for getting the most out of it

Adding too many items shrinks the text and makes it hard to read, so we recommend keeping it to around 10 items per screen. If you have a lot of candidates, try a "two-stage roulette": spin once to narrow down to a broad category, then spin again within that category.

Letting the wheel decide takes the pressure off any one person for "who chose this." That's the big advantage of a roulette wheel — everyone finds it easy to accept the outcome.