Candling Chicken Eggs – Is A Chick Growing In There?

When incubating eggs, or when a hen is sitting on a clutch, there is a way to find out whether or not a chick is actually growing in there. This process is called candling.

Long ago, it was actually done using candles, but nowadays there are many different ways to do it. You can buy special egg candling equipment, or simply rig something yourself.

The idea is to shine a very bright light through the eggshell in a dark room, which illuminates the shell, and allows you to see what’s going on inside!

fertile and infertile eggs diagrams
Egg diagrams showing fertile and infertile eggs. Photo from Carla Emery’s book The Encyclopedia of Country Living.

Tonight, we candled our 15 eggs. What we used was very basic- a desk lamp and a small box. In the top of the box we cut a hole, just big enough that the egg could barely sit down in it without falling through.

We laid the lamp down on a table, and put the box over the light bulb. With all other lights off, we put each egg, one by one, over the light shining through the hole in the box.

candling box

You guys, this is so exciting! It’s almost as good as seeing a sonogram! The light shines through the eggshell, and if it’s fertile, you will see a little chick growing (and moving) inside! I squealed with excitement when I saw that first little chick moving within its shell.

After 72 hours of incubating, you should be able to easily distinguish between fertile and non-fertile eggs. The good ones will have spider-like blood vessels spreading within (see picture above). It’s best to candle early on; if you have an egg that is obviously not fertile, it is still safe to eat after being incubated for up to nine days.

I wish we would have candled our eggs sooner, though. Ours have been incubating for two weeks now, so the chicks are quite developed. Once the chicks are so far along, they appear to be a large dark mass within the shell.

Some of mine moved, so it was easy to tell that a chick was alive in there. But others just looked like a dark shadow. I’ve had a very hard time distinguishing between good eggs and bad ones.

It wouldn’t be such a big deal to just leave them alone, but I read that the bad ones can rot and actually explode- spreading bad bacteria all over the other eggs, and making a big, stinky mess in the incubator!! So I definitely want to get the infertile ones out.

There are some eggs that I think are bad, but dang, I’d hate to throw one out if it’s actually alive!!  I’m gonna have to candle them again and really take a close look to determine whether they are in fact growing or not.

8 thoughts on “Candling Chicken Eggs – Is A Chick Growing In There?”

  1. Hi Kendra,

    I’m also having such fun candling the eggs of our two broody hens. I just go outside with the flashlight and cup the eggs one by one.

    I’m not so happy today, however, as the Marans hen keeps moving her eggs around, they crack, then she eats them. It’s not the end of the world (well, I guess it is for the chick that may have been developing) I know this occurs regularly in the chicken world, but now she’s down to just one. Have you ever had that happen, or do you always use the incubator? This saddens me just sitting here writing this all out. I’ve got her separated from the other hens (there are only 3 females in all), but if this last egg goes the same way, then what does one do with a broody hen? Sigh.

    • Tammy,

      Sorry to hear about your dilemma!! None of my hens have gone broody, and this is our first batch of incubator eggs, so I’m afraid I have no advice for you. Maybe one of my readers will though. Hopefully since it’s the last egg it won’t have anything to crack against and it will make it. That would be terribly frustrating!!

  2. Hey Kendra,
    How exciting!!! What kind of chickens are you raising? We have 2 golden comets, a bared rock, and an Ameraucana. We don’t have a rooster, so we won’t be having any chicks…..just lots of eggs!! 🙂

  3. Hey Kendra,
    How exciting!!! What kind of chickens are you raising? We have 2 golden comets, a bared rock, and an Ameraucana. We don’t have a rooster, so we won’t be having any chicks…..just lots of eggs!! 🙂

  4. Hey Kendra,
    My husband and I also candle our eggs using a bright flashlight and just our hands. One of us will cup our hand(s) around the end leaving a little circle at the thumb and forefinger, while the other moves the eggs over the light. We usually do this in the evening down at the chicken house after the chickens have tucked themselves in for the night.

    I wouldn’t eat an egg that has been in an incubater for 10 days. If you don’t want them to go to waste, cook them up and serve them shell and all back to the chickens. I haven’t had rotten eggs explode on their own under a chicken or in an incubater BUT once I’m sure they aren’t viable and I toss them up against a rock MAN do they ever exlpode with noxious nastiness!!

    Here are a few things that I picked up along the way: First, you can look really close on the large end, in the rotten eggs, you’ll be able to see the air sac. A freshly laid egg doesn’t have that sac, it is acquired over days and weeks as the egg shell allows moisture to escape. Second, rotten eggs will typically weigh less than ones with chicks in them. We can usually tell by holding them but you could also use a diet or postal scale. A final test before you crack them open would be to try floating them in water just like you would if you found a cache of unincubated eggs. Remember that a part of the yolk will stay with the chicks up to 24 hours before they hatch b/c they suck the yolk up for that last umpf of energy that they need to break out of the egg so don’t let its appearance fool you into thinking there is no chick. And even rotten eggs will fool you into thinking that there is movement, those darn gasses will cause that yolk to swish and move around when you are candling them. Hope that helps!

  5. We have had great success with candling our eggs. We simply use a flash light and a dark room. My husband holds the egg in his hand and puts the flashlight to one end. This is a great link to see pics and explanations about the various things that can happen to eggs… I just had 2 Peking ducks hatch the day before yesterday and have more to go. We are hatching chickens, ducks, guineas and turkeys. Happy hatching..


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