I don't know if there is an exact answer to that question. Unwashed eggs will last a couple of weeks on your kitchen counter at room temperature without losing too much quality. Stored under refrigeration probably a couple of months, maybe longer if they are unwashed. After that you can always crack and freeze them--they lose some quality but are great for baking. Obviously washing, since it removes the bacterial protective "bloom", shortens shelf life to the point were all washed eggs have to be refrigerated--the USDA requires producers to wash all eggs, that is why they are labeled "keep refrigerated".
On the other hand, they don't last long around here at all: they are either eaten immediately, shipped off to my daughters' or snapped up by local customers. I can't remember a time in 25 years where we've had an egg go bad.