why do (most) dice have the same face placements? As in, why is the 6 usually opposite to the 1, likewise with the 3 and 4? Does this affect the “fairness” of a dice roll, making it a 1/6 chance every roll as opposed to a different value?

In: 576

Mostly it’s just tradition. It actually can affect the odds, if you aren’t careful about distributing the die’s mass evenly among all six sides, which is why casinos fill in their dice’s holes using a resin of the same density used to make the dice themselves. But for most gaming dice, the effect isn’t large enough for people to care about.

You’re asking about rolling dice versus counting dice. While it’s not very obvious with a six sided dice, a 20- sided die is usually put together the same way, so that opposing sides sum to the same number, and adjacent sides are farther apart. Some such die have numbers next to each other so it’s easy to turn the top face from 20 to 19 to 18, etc. With some practice, you could roll the counting die to give your preferred high or low result.

It’s a bit more than tradition.

If your dice is not perfectly equilibrated (e.g. one half is heavier than the other and these faces will show up less often), then opposite face adding up to always the same number (7, on six-faced dice) will ensure that the mean outcome will still be the same.

The pattern is so that the two sides opposite eachother will always add to 7.

Is there any real reason for this? Not really, it’s just how they have always been done.

Tradition. And no, it in no way affects the outcome, no matter what you put on a face as long as the faces are identical in weight