Before incubation, a fertilized egg can be stored for a maximum of 7-10 days in a cool room kept at a steady 15 to 18 °C  (not in the refrigerator – it’s too cold!). Once the fertilized eggs are placed in the warm incubator, they will start to develop over the course of 21 days, with the proper incubator set up and care.

Before your baby chicks hatch, be sure to stock up on chick starter feed. A newly hatched chick will need free-choice access to food and water immediately once they hatch and are placed in the brooder.

How to set up the egg incubator

Fertile eggs can be hatched by using an egg incubator. An incubator is an enclosed structure with a fan and heater to keep eggs warm during the 21-day incubation period. When determining which incubator to purchase, we recommend using an incubator that has automatic features, such as an egg turning function - which is critical to chick development and to keep the chick from sticking to the inside surface of the shell, temperature and humidity control, and a fan to facilitate even heat distribution.

The incubator should be prepared one week before the arrival of fertilized eggs and should be positioned in an area out of direct sunlight, where ambient temperatures are steady, and with no risk of draft. Once you have positioned your incubator you will need to start the cleaning and disinfection of your incubator. 

To clean your incubator, you should wash it using a 10 % bleach solution, followed by warm soapy water and a thorough rinse. Lastly, spray the incubator down with a disinfectant solution such as Virokill (mixed as per manufacturer's instruction) to ensure you’re starting with a sanitized environment. 

Once the incubator is clean and dry, turn it on and check to ensure that a constant temperature and humidity level is maintained. 

Temperature and humidity inside the incubator are critical factors for successfully hatching eggs. 

Suggested guidelines are as follows:

Day 1: Setting eggs

Once you have the incubator set up and have analyzed the settings to ensure accuracy, you are ready to place the eggs inside the incubator. This process is called “setting the eggs.”

Plan to set a minimum of six eggs at one time. Setting fewer eggs, especially if the eggs were shipped, often results in one or no hatchlings. The number of chicks that hatch together is especially important for newborn chicks because chickens are flock animals and need companions to be happy. Remove eggs from the cardboard carton into the egg tray of the incubator, with the widest end facing up and the narrow end facing down in the incubator egg tray.  As a reminder, the incubator settings should be set to 37.5 °C (temperature) and 50-55 % (humidity).

After setting the egg trays and returning them into the incubator, the incubation process begins. An important part of this incubation process is turning or rotating the eggs.

Day 1-18: Turning the eggs

Eggs must be physically turned to prevent the developing chick from sticking to the shell. More scientifically, the embryo should be resting on top of the yolk. The yolk tends to float upward, on top of the albumen (egg white) towards the shell if the egg is not turned. As a result, the developing embryo can be squeezed between the yolk and the shell, causing potentially fatal damage. By turning the eggs, the yolk turns within the albumin, once again moving the yolk away from the shell and making it safe for the embryo on top until it is time to turn again.

Eggs will need to be turned a minimum of 3 times per day, and 5 times is even better. If you are turning the eggs manually, it is advised to gently make a mark with a pencil (never a pen!) that will help you keep track of which eggs have been turned. If you have an automatic incubator, it should turn the eggs for you and eliminate the need to open the incubator repeatedly (check the user’s manual).

Be sure to wash your hands or wear clean gloves before you touch the eggs to prevent the transfer of skin oils or germs to the developing embryo.

Days 7-10: Candling eggs

Towards the middle of the incubation period at 7 to 10 days, eggs can be candled to determine if the embryos are growing properly.

Candling is the act of simply shining a light through an egg. White and light-colored shells are the easiest to candle, while darker shells will require brighter/stronger light. The simplest way to candle an egg is with a basic torch, but specialized pieces of equipment are designed specifically for the job.

Do not keep the egg out of the incubator for more than 5-10 minutes, allow the eggs to stay inside the incubator, plan to candle a few at a time.

If you have a large number of eggs, do not candle all the eggs all at once, select a few to get an indication of growth.

If the inside of the egg is clear - that is, free from visible structures or dark areas - the egg is infertile, or the embryo died very early. Remove this egg from the incubator.

If a ring of red is visible within the egg, there was an embryo at some point, but it has died. Remove this egg from the incubator.

If you can see blood vessels within the egg, there is a live embryo inside. Blood vessels in chicken eggs are normally observable within 7 to 10 days of an egg's incubation. By 18 days of incubation, the embryo takes up most of the egg and appears as a dark area within the egg. You can sometimes see movement inside the egg.

If you notice broken or leaking eggs, remove them from the incubator as they are not likely to be viable and may contaminate the incubator. After candling, return eggs to the incubator and return to the day 1-18 turning schedule.

Days 18-21: Pre-hatching

By day 18, the embryo has developed into a chick and will take up most of the space in the egg. The chick is preparing to hatch. You can do a few things to best help the baby chick prepare:

Stop egg-turning at day 18, Remove the eggs from the egg setting tray into the hatching basket so that the eggs can lay flat. Do not overcrowd the basket as this will hamper the chick's ability to wiggle out of its shell on day 21.  

Maintain a temperature of 37.5 °C but increase humidity to 70 %.

Day 21: Baby chicks start hatching

Chicks will typically hatch at day 21. If you are at day 21 with no hatch or eggs were cooled before incubation, the process might take a little longer, just give the eggs a few more days to hatch.

When the big day comes, let the chick hatch on its own. Do not attempt to help. Blood vessels that haven’t dried up yet may still attach the shell to the chick, and prematurely pulling off the shell can cause excessive, potentially fatal, bleeding. A chick can take up to 24 hours to completely hatch, although 5-7 hours is more common.

The peeping and chirping of the new baby chicks will encourage unhatched eggs to also start hatching. When the chicks have all hatched, the incubator temperature can be lowered to 35 °C. Once the chicks have dried, they can be moved into the brooder, which should already be up and running with a temperature of 32-35 °C. Food and water should be in place and ready as well.

If there are still unhatched eggs at day 21, don’t despair. It is possible that timing or temperature went slightly awry, so give the eggs until day 23. Candle any unhatched eggs to see if they are still alive before discarding them.

Keep in mind that when hatching eggs, you will likely end up with roosters. There is a 50/50 chance that a chick will be born a rooster. There is no good way to determine if a male or female chick is developing inside an egg.

If you decide to keep a rooster, it is suggested to only have one. In addition, 1 rooster per 10 hens is typical for continued breeding. Any less than that can put hens at risk for overbreeding and injury.

Hatching eggs can be a very rewarding experience with proper planning and equipment. Remember to test all equipment before fertilized eggs arrive and set up the brooder as hatch day approaches.

Timeline for the embryo growth during 21 days.

egg development