nesting boxes!?!?

[Thortherooster]

so I have 25 chickens and only one of them is a rooster, so if i am not hatching eggs, about how many nesting boxes should i have for them?? i have no idea, will they share?? i have 2 R.I.R, 2 silkies, and rest are black star, and the rooster is a R.I.R.
Thanks....

 

[frogs n chickens]

3-4 chooks per nest so 8 should be a safe bet; I have 4 for 9 ladies.