How long can eggs stay fertile for?

[yanks26]

How long after the chicken lays the egg will it remain fertile? And what must I do to keep them fertile?

 

[duckyfromoz]

There isnt so much a set number of days days - but generally after 7 days the viability of them being able to hatch does start to decrease. I keep mine in a cool room inside the house until I set my eggs.