Board game dice don’t always play fair

Here’s the secret behind dice design.

Julia Bernhard illustration
At Midwest Game Supply Company, dice are produced as “certified perfects” in which each side of the dice is flat, making results from a toss as haphazard as possible.Julia Bernhard

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Linda Sohm is a co-owner of Midwest Game Supply Company. Here’s her tale from the field as told to Sandra Gutierrez G.

The dice in your Monopoly set aren’t as random as you think. The black dots that number each side are hollow, so faces with more spots weigh less. When you roll, it’s more likely that a heavier side will land facedown, meaning you have a greater chance of getting a six than a one, or a five than a two. My company is the only manufacturer in the United States that produces “certified perfects”: Each side of one of our dice is flat, making results from a toss as haphazard as possible.

Instead of filling sets of molds like those used to mass-produce dice for board games, our plastic—a strong polymer called cellulose acetate commonly found in eyeglass frames—feeds into an extruder to produce something like a long, square spaghetti strand. We use a bandsaw to create individual cubes, then hand-drill all 21 dots to the same depth. Next, we fill each spot with epoxy to replace the missing material, and polish the edges—all while maintaining the standard size down to one-ten-thousandth of an inch.

I haven’t been to a casino in years. Even so, as an expert in how these pieces will roll and fall, I know winning a big pot still requires a significant amount of luck.

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