How many eggs do chickens normally need to want to hatch them all?

[daisychicken]

My hen laid an egg and was a little broody but she left. Later today I read naturally they wait until they have enough eggs to sit on them so they hatch at the same time. As an estimate how many eggs will she need to stay on them?
This is the hen,

 

[ChickenAndMore]

Mine usually start incubating when they have about 15 eggs.

 

[sumi]

I had a hen that were prone to broodiness, so I let her do her thing and each time she collected a clutch of 12 eggs before she started sitting except once, when she laid 13. I also had hens lay up to 18 eggs in hidden nests and letting them go off. They were simply not interested in brooding them. It depends on the individual hen, the breed (some are more prone to broodiness), hormones and the time of the year (they go broody more often in Spring and Summer, though I've had broodies in the middle of winter). What you can do if you would like your hen to hatch some chicks for you, is to leave a few "bait" eggs in the nest for her, real or fake eggs, just mark them if they are real, so you can collect the fresh ones daily. Leave them there and see what she does. She may fall for it and decide to go broody, or she may not. That really is all you can do. Don't let her pile up a large number of eggs though. Keep it to a few only, so if the experiment doesn't work out, you haven't lost much.

 

[daisychicken]

I read when they start setting they stop laying eggs but I'm not sure if that's true.

 

[donrae]

I read when they start setting they stop laying eggs but I'm not sure if that's true.

That is true. I usually put anywhere from 5-8 bait eggs in the nest to see if she wants to brood. Then just decide how many I want her to brood for real. My broodies are bantams and my hatching eggs are large fowl, so the most I give my little girls is 8.