How wide is a chicken?

[GuerrillaChickenArmy]

We just got six Golden Comet pullets, and I built some nest boxes out of plastic tubs from KMart....the dimensions are 13"x14", but the entrances are only 7.5" wide by 10"tall...

Is this too narrow? How wide is a chicken?

Some photos of the nest boxes here:
http://freechickencoop.blogspot.com/2009/05/nest-boxes.html

 

[The Chicken People]

Should be fine but if need be can you cut them out wider since they are plastic? One of my pullets is a rooster!

 

[jenjscott]

I think you'll be ok. Mine seem to like a smaller opening. A little more seclusion I think.