how long can eggs survive unincubated?

They are fertile for seven days after being laid.And if I'm correct it has only ben 4?

I'm not really sure about chickens, but maybe this holds true as well. For wild birds the females won't set on the eggs until they are done laying to ensure they all hatch around the same time. I would say they may not have as great of a hatch rate, but it is still definitely worth a try hatching them. I'm no expert though! Good luck!

I've hatched 2 weeks old eggs with 100% hatch rate.  Fertility starts dropping after the first week - but I've read of people successfully hatching chicks from eggs even 3 weeks old.   Without human interference a hen might lay eggs for a couple weeks in order to get a large enough clutch before she starts brooding them.   There are a lot of factors other than age that can affect fertility.

I was wondering the same thing. I want to set eggs on Feb 6th so that they will hatch for my sons science fair... I want to get eggs from someone that ships on Mondays so I can either have eggs shipped to me Jan 28th and they will have to sit for a week or so or they can be shipped on Feb 4th and I probably wont be able to set them on the 6th and that will leave me with no room for error. They will be shipped so I was thinking sitting for a week might be good if air cells detached during shipping?! Would I keep them at room temp during that week before I can set them? I know I should still turn them up until I can set them.

The fresher the egg the better it's chance of hatching, but there are other factors, like temperature, humidity and of course, how they got handled... Shipped eggs are always a bit of a gamble. With them I'd be more concerned about the condition of the air sacs than the age of the eggs! Here's an interesting article on egg storage before incubating if anyone's interested:

http://www.pasreform.com/academy/frequently-asked-questions/hatching-eggs/16-storage-of-hatching-eggs.html

And Sally Sunshine put together another great article on incubation with some notes on shipped eggs, which I think you'll find interesting too:

http://www.backyardchickens.com/a/hatching-eggs-101

Thanks for the links. Very useful. 

When shipping eggs or ordering eggs, always note the Sunday in the shipping time frame.  Also, always note the holidays when PO is closed that may fall within the shipping/receiving time frame.  These things can sneak up on folks.  Just as a rule, most egg shipping is normally done on Tuesdays to forgo shipping delays. All the OP can do is go ahead and incubate.  Once an egg is laid, the clock starts ticking.  Then there is collecting...  tick, tick,, tick

Then packaging and taking to the Post Office... tick,, tick ... tick

Then shipping and picking up..... tick.... tick...   Then resting for a day..... tick... tick.  

This is why shipping eggs often results in slightly lower hatch rates.  Comes with the territory.