The Flip

The flip is one of the more esoteric rituals in ultimate but it can have a large impact on the game as it determines which team starts on offense/defense and which side of the field each team starts at. In this page I will share what is theoretically the best way to call the flip and my thoughts on how you should approach the choices resulting from the flip.

WINNING THE FLIP 

By winning the flip, I actually mean possibly getting a slight probabilistic edge when calling the flip that is likely only perceptible over the course of hundreds of recorded flips. (But the math is sound, trust me)

Essentially if you are calling a flip with two discs, you should call "same" AKA "even". This is because if there is any bias from flipping a single disc, which there likely is due to its asymmetrical shape, the probabilistic sum of both discs landing heads or tails is greater than the combined chances of both discs landing on different sides, regardless of whether tails or heads is more likely (I'll get to this in a bit). The math is explained in this article written by a player from Stanford lol.

If you are calling a flip with one disc, I think "tails" AKA "down" is more likely on soft, even surfaces like turf and well-kept grass due to the curve on the top of the disc creating more surface area for the disc to land on. However on hard, rough terrain I think there's a greater likelihood of the edge of the disc "catching" on the rough ground and landing "up" AKA "heads". A number of people have experimented on different surfaces with conflicting results but my reasoning largely follows this skyd article.

Offense/Defense/Starting Side

Here is flowchart detailing how I would navigate the post-flip decision: