You might think that getting one of those 10km eggs in Pokémon Go means it'll yield something rare and exciting — especially after all those new Pokémon were added in the Gen 2 update — but it looks like that's not the case at all, according to new crowdsourced research from Pokémon Go community the Silph Road.
In fact, the research suggests Pokémon hatched from eggs belong to one of four "rarity tiers," which are not always related to the amount of walking they require to hatch.
Let's dive in.
Pokémon Go egg chart: Research suggests eggs are sorted into four "rarity tiers"
According to the research, there are four tiers into which eggs are sorted, each of which is two times as rare as the tier below it.
"In simple English, this means that not all 10km egg species are rarer than 2km egg species or 5km egg species," the Silph Road report says. "A simple example of this is that Dratini is presently a very common hatch, despite being in 10km eggs. It is currently easier to acquire a 10km egg with a Dratini inside than a 2km egg with a Machop inside."
The research included a chart showing which tier each type of Pokémon belongs to, which we've reproduced below. It's likely that these categorizations will change over time as more data comes in, particularly in the higher rarity tiers.
So, the good news is that you shouldn't get too frustrated when you get one of those 2km eggs — but it also means that it's impossible to see, at a glance, whether or not an egg will contain an exciting Pokémon.
In theory, the egg rarity tiers should correspond exactly to the distances — you know, more walking equals a better Pokémon — but it just wouldn't be Pokémon Go without something shrouded behind hidden data, now would it?
Read the full Silph Road report for all its findings.
More Pokémon Go news, updates, tips and tricks
Check out Mic's Pokémon Go tips and tricks. Here are guides on how to get stardust, how to determine how long it will take you to reach level 40, the kind of Pokémon you get from 10km eggs, how to create new PokéStops, how to maximize your chances of catching Pokémon and how PokéStops distribute Pokémon eggs. Also check out how to catch Gen 2 baby Pokémon, our analysis of post-balance update Chansey and Rhydon and everything you need to know about finding the long-awaited Pokémon Ditto.