chicken door to coop - ? size

[blueheaven]

what size should i make my door on the cook for the hens to go into the run?
i want to make it slide so i can close it from the outside.

i will have 10 standard hens (i get my pullets in 6 weeks)

thanks...

 

[briteday]

My door is about 10 x 10 and my RIR's get in and out jsut fine.