Are eggs predetermined before you hatch them?

In Pokémon Go are eggs predetermined before you hatch them? What I mean is, has it already been decided what you are going to get from that egg before it's been hatched? Or is it a random selection during the hatching?

Yes, they are already predetermined (experience and research from thousands of players over at the subreddit /r/pokemongo).
This is so, because no matter at what level you are right now, the Pokémon that hatches is limited by the level you were when you got that egg.

Example:
You are level 10 and get an egg.
Now at level 20 you decide to hatch it.
It will be as strong as limited by level 10 and not level 20, because it's already predetermined (like in the original Pokémon games)

• What evidence do you have to support this? It doesn't seem right. Aug 10, 2016 at 4:18
• @Frank Personally I think he's wrong. Just because the CP is the same only determines that the CP is chosen already, that doesn't mean that the Pokemon has been chosen. Aug 10, 2016 at 15:01
• I'll give you the bounty but I won't accept the question, I still don't see any proof that you're correct Aug 31, 2016 at 20:26
• Since the game itself doesn't provide a way to tell this, you'd need access to the code to see how inventory items (or in this case, Pokemon) are defined and implemented to make this assertion. Otherwise, you can't really make this claim. The way the game treats eggs allows for a very wide variety of ways to implement them in the code. So without something that says, "Hey look! Here's the species for this egg", you don't really have any verifiable answer here. Aug 31, 2016 at 22:33

There are now numerous indications the contents of an egg is predetermined.

• As mentioned in the question, Eggs have a Pokemon ID number, which continues to be their number after they hatch.
• As mentioned in GiantTree's answer, the level of a hatchling is determined by the level you had at the time you attained the egg. It is equal to your trainer level at that time, up to a maximum of level 20.
• Movesets are apparently determined at the time you find an egg. This was evidenced by the patch on August 19th, which effected changes to the moves that could be found in several species. Some eggs generated before this change were found to have legacy movesets. Note that this means the species of the Pokémon was also pre-determined.
• A Pokémon's geographic origin is, for hatchlings, attributed to the location their egg was found.
• During the Halloween Event at the end of October, the spawn rates of certain spooky Pokémon like Meowth and Ghastly was vastly increased. The eggs which people had stockpiled prior to the event contained ordinary assortments, but those who hatched enough eggs to pick up several during the event reported that their contents adhered to the Halloween spawn rates.

This really only leaves IVs as an attribute which could be sensibly left until the hatch event to be determined. That said, good data has consistently shown egg IVs to be evenly distributed between 10 and 15, and no rigorous means of affecting these stats has been documented thus far.

Programmatically, it would make the most sense that Eggs actually are Pokemon, already, and that their various attributes simply aren't transmitted to the game client until they're hatched. This is supported in various ways:

• By exploiting the deobfuscated game API, there was a short period where hackers were able to place eggs in gyms, exactly as though they were Pokémon. (Because their combat parameters were obscured, a fight with these prenatal defenders resulted only in errors, and they were an intractable problem until Niantic saw to the problem)
• Eggs count against the general limit of a player's Pokémon box. Seriously, go count.
• For many weeks after the game's release, egg hatching events were not logged in the player's journal. This makes sense if you consider that the egg hatching event is not actually the moment the Pokémon is added to the player's inventory.

Probably some other circumstantial evidence, too.

There is one contrary point I can think of:

• A hatchling's time of acquisition is set to the moment they hatch, not the moment their egg was found. I think this is actually coherent with the theory, however, given that hatch events were not initially reported in the player's journal; by setting the Pokemon's date of acquisition to its hatch date, the game ends up sorting it as a recent event and then displays it as such in the journal.
• Your 3rd bullet point is, quite easily, the most compelling piece of evidence that Pokemon are pre-determined when you receive an egg. Everything else (the Pokemon ID, level, origin, Pokemon count) could easily be implemented just for eggs, and then the Pokemon species and moveset could be added at hatching time. But if Pokemon eggs are hatching with species and movesets that are no longer possible for new Pokemon, then that's a really strong indicator. Sep 25, 2016 at 8:37

I had a friend log into my account overseas. I had no eggs, all were hatched I asked that he fill my account up on Pokestop eggs. A day later I logged in back in the US and some of my hatches were region specific hatches I can't get in my state. This proves the type of egg is decided when you get it, not when its hatched, otherwise I would not get region specific Pokemon.

Yes, the Pokemons which are going to spawn from the egg are already predetermined as soon as you obtain the egg. And you've yourself provided an evidence to support this - the Pokemon ID associated with the Egg.

• Do you have any evidence to prove that this is correct? The ID I was able to obtain only proves that there's a Pokemon inside of the egg and nothing more. Aug 24, 2016 at 9:26
• Not gonna argue about the pokemon predetermination, but the CP part is incorrect. Hatched CP is calculated from trainer level at the time of receiving the egg. Tested myself when I kept egg from level 10 and then hatching egg from level 22. Aug 24, 2016 at 10:50
• @Zikato thanks for bringing it to notice. Answer updated. Aug 24, 2016 at 11:13
• Since eggs count as a Pokemon in terms of storage space, the fact that it has an ID is only logical from a technical standpoint. But there's absolutely nothing there to show that other things have already been generated as well, like species. Aug 31, 2016 at 21:09

Yes they are (according to that code and some research)

Example: If you had a 10km egg you could have a Jynx

• According to what code? And we know that a 10km egg could hatch a Jynx. That's not what's being asked. The question is: when you get an egg from a Pokestop, is that egg already a Jynx that needs to be hatched, or does the game turn the egg into a Jynx once the egg is ready to hatch? Sep 2, 2016 at 20:12

Yes, what Pokemon you're going to get from an egg is predetermined when you obtain it. This is known because if you obtain an egg at level X, the level that you hatch it at does not affect what you get.