What age is a duck considered as fully grown?

[Indyrun]

My ducks are nearing the 2 month mark and are still shedding and one is still doing baby chirps.

One website I read stated that a duck is fully grown in 30 days! Well that is clearly not the case here.

 

[toowoombapekins]

I also read the 30 day thing somewhere too.
But my pekins were only around half the size they are now at 30 days. So definitely not the case with pekins anyway!

I keep reading recommendations to put them on adult feed at 20 weeks. So I'm figuring that's about when they are considered as adults and/or fully grown

 

[Going Quackers]

By 9wks according to Storey's guide most have reached 70-90% of their adult body weight. Now some breeds do vary somewhat with the development but 30days? the feathering isn't complete at that age.. more in the next few weeks... but more bulk will add as they move through that second month.

 

[Amiga]

Oh, my. My ducks were close to full sized at 4 months. They were fully mature, I would say, by around 7 to 9 months.

These are runners.