Size of Pen for Chicks

[AM-Farmer]

I recently purchased around 45 baby chicks from a hatchery and they are due to arrive Aug 15. I wanted to keep them in a pen until they are ready for the full size coop, but I don’t know how large of a pen I will need to keep them in. I have found plenty of info for the size of the coop and the chicken yard, but not a pen for baby chicks. Any help would be greatly appreciated.
Michael

 

[HenMamma]

The first couple of weeks they need .5 sqft per chick. after that they will need 1sqft per chick. With more room as they grow larger.

 

[Wynette]

AM-Farmer - for the first 3 days, I had mine in an old horse trough. Mine were a wee bit crowded at first, but when they turned 3 days I moved them into a larger area, as HenMamma indicated.

Make sure not to put them on shavings until they are at least 3 days old; use newspapers or paper towels, some folks use old towels because newspapers can be slippery. Good luck, and:

 

[AM-Farmer]

Thank you both so much.

 

[Mahonri]

I used paper towels for the first 3 weeks. It just made things easier. Then I added the pine shavings.
I had 19 chicks... small card board box to begin with, then one 3 times as big. When they could jump out of that, they were ready to have the run of the coop (an 8X12) At 5 weeks I let them out into the run although a couple of them could squeeze through the wires.