Egg Candling Guide for Incubating Eggs.

Are you incubating eggs? Then you should learn egg candling! Candling eggs allows you to keep track of the progress of your egg incubation.

Using a special high-powered torch you can monitor many things including the egg fertility, embryo viability and moisture loss (humidity).

By being able to identify and remove non-viable incubating eggs you can also avoid the risk of a rotten egg exploding and contaminating your hatch with dangerous germs.

And candling does not harm your eggs.

Just as the mother would naturally leave the nest for a short time each day, you can safely take your incubating eggs out of the incubator for up to 30 minutes, for the few times you will be candling them, without harm.

The Egg Candling Torch

Using a Candling Torch that throws out a strong, focused beam of light will make the job a lot easier.

Your Candling Torch should also put out a cool light rather than a lot of heat that might damage your embryos.

Why choose our Luxeon torch for your egg candling?

Luxeon is the world's brightest LEDs in the smallest form. The benefits for candling eggs are

* No heat - won't damage your embryos.

* Compact, and light weight.

* Super efficient and only need a single AA battery.

* Long operating life - Like all LEDs, it has an expected operating lifetime of 100,000 hours. That's basically 22 years, if you used it 12 hours a day!

We ship promptly, worldwide - get your Candling Torch here.

Egg Candling Procedure

The best time to candle your eggs is in the evening, or anytime you can take advantage of dimly lit conditions.

Equipment needed:

• Egg candling torch

• Pencil

• Egg cartons


1. Remove all eggs from the incubator and place in egg cartons.

2. Dim the lights.

3. Hold each egg, one at a time, against a Candling Torch.

4. Discard non-fertile eggs (“clears”) or those that have stopped developing (“quitters”).

5. Return viable eggs to the incubator.

It will take a little practice to become a confident candler. Any eggs you are not sure of, pencil a question mark onto. Have another look at them later. Comparing them to your good eggs will help you decide.

Break open the rejected eggs to reconcile what you saw with the candling torch and what is actually happening in the egg.

Here is a “clear” or non-fertile egg.
If you get more than 20% like this, old or poorly stored eggs, high hen to rooster ratio, inbreeding, or improper parent diet could be to blame.

This will give you greater confidence and be a great learning tool.

Bear in mind, the inside of white eggs with thin shells is easier to see with the Candling Torch than that of darker colored eggs and those with thicker shells.

Egg Candling Timeline

Start candling your incubating eggs at day 4 of incubation.

In fertile eggs you will see a small spot (the embryo) with a web of blood vessels radiating out from it.

A fertile egg at day 4 of incubation

Conversely, infertile eggs will either be clear, or show a dark ring.

This video shows an embryo alive and kicking at day 7 of incubation:

This video shows a viable chicken egg at day 12 of incubation. Obviously it would be a lot easier to see the embryo if they had a decent candling torch!

By day 18 the embryo will take up most of the egg (apart from the air sac). When raising chickens eggs they should not be candled after day 18.

Egg Candling and Air Sac Development

egg candling

During incubation the air sac size should increase as moisture evaporates from the egg. If your humidity levels are about right, the air sac should increase at different days of incubation according to the diagram shown here.

If the incubation humidity is too high, the air sac will be smaller than it should be. If humidity is too low (i.e. very dry conditions) the egg will lose more moisture than it should and the air sac will be larger than normal.

Click here for more information on egg incubation or hatching chickens.