I just watched Alien and when the alien leaves the host it's tiny.

A few minutes later in the movie they encounter the alien and it's now fully grown and is larger than a human.

I don't know how much time actually goes by in the movie but it couldn't be more then a few hours, it seems to grow extremely fast. How fast does it actually grow?

3 Answers 3


According to the Alien Wiki "Maturity is reached in a few hours, and involves a dozenfold increase in mass..."

Given that it takes only a few hours to go from being face hugged to having one burst out of your chest, it looks like they can go from embryo to adult in only 6-8 hours.


They grow from embryo to adult in about 2-3 hours max. However a queen may have taken 6-7 hours.

  • 2
    Can you cite a source or a timeline for that? (Preferably a more canonical one than the wiki link in the above answer.)
    – DavidW
    Commented Feb 8, 2021 at 17:24

The alien in the first one was just a drone. Now if you are counting the time the facehugger was on there it might be at least 6-8 hours. But however the facehugger only needs an estimated 30-60 seconds to impregnate a host. But the xenomorph is growing inside the host. I was counting the amount of time outside the host. If I was counting time inside and outside the host it would be 6-8 hours.

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