21-Day Chicken Egg Incubation Guide

Hatching chicken eggs is an exciting hands-on experience for families, classrooms and young learners. Over 21 days, a fertilized egg develops from a tiny embryo into a chick ready to hatch.

The key to a successful incubation is consistency. Keep the incubator at the correct temperature, maintain appropriate humidity, allow the eggs to turn regularly and avoid unnecessary opening.

For Hatchables chick hatching kits, follow the guide below along with the instructions included with your rental.

Chicken Egg Incubation at a Glance

Incubation period: approximately 21 days
Temperature: 37.5°C / 100°F
Humidity Days 1 to 17: 45% to 55%
Lockdown begins: Day 18
Lockdown humidity: approximately 60% to 70%
Expected hatch: around Day 21

Chicken eggs are normally turned throughout the first 18 days. Turning stops during lockdown so the chick can position itself properly for hatching. University poultry guidance also identifies approximately 21 days as the normal incubation period and Day 18 as the point when turning should stop.

Day 1: Set Up the Incubator

Place the incubator on a stable, level surface away from direct sunlight, heaters, air vents and drafts.

Before adding the eggs:

• Set the incubator to 37.5°C / 100°F
• Bring the humidity to 45% to 55%
• Make sure the incubator is level
• Confirm the automatic egg turner is operating
• Make sure the lid closes properly
• Allow the incubator to stabilize before placing the eggs inside

With a Hatchables kit, we recommend allowing the incubator to warm and stabilize for approximately three hours before adding the eggs.

Small fluctuations can happen when the incubator is first warming up. Avoid making constant adjustments while it is settling.

Day 1: Add the Eggs

Once the incubator is stable, gently place the fertilized eggs inside.

Handle the eggs with clean, dry hands and avoid shaking them. Once they are inside, close the incubator and give the temperature and humidity time to recover.

For the first part of incubation, your main job is simple:

• Keep the temperature around 37.5°C
• Keep humidity around 45% to 55%
• Make sure the automatic turner continues working
• Check the incubator daily
• Avoid opening the lid unnecessarily

The temperature may briefly fall after the eggs are added. This is normal. Give the incubator time to recover before changing its settings.

Days 2 to 17: Keep Conditions Stable

During these days, the embryo develops rapidly inside the egg.

Try not to constantly adjust the incubator. Stable conditions are more important than chasing every small change on the display.

Check that:

• Temperature remains close to 37.5°C
• Humidity remains between 45% and 55%
• The turner is operating
• The water system has enough water
• The incubator remains away from drafts or direct sunlight

Egg turning is especially important during early development because it helps prevent the developing embryo from remaining against one side of the shell membrane.

Candling Chicken Eggs

Candling allows you to shine a bright light through an egg to observe development inside.

Hatchables provides a candling light with its kits.

When candling:

• Use a dark or dim room
• Keep your hands clean and dry
• Handle each egg gently
• Keep the egg out of the incubator only briefly
• Return it carefully when finished

As incubation progresses, you may see blood vessels, a dark developing embryo and eventually movement.

Not every fertilized egg will necessarily develop or hatch. Hatch rates can vary naturally even when incubation conditions are carefully maintained.

Day 18: Lockdown Begins

Day 18 is one of the most important points in chicken egg incubation.

At lockdown:

• Stop turning the eggs
• Remove or disable the egg turner
• Gently place the eggs for hatching
• Increase humidity to approximately 60% to 70%
• Maintain approximately 37.5°C / 100°F
• Keep the incubator closed
• Do not candle the eggs

Chicken embryos begin positioning themselves for hatching during these final days, which is why turning is stopped around Day 18.

Try not to open the incubator once lockdown begins. Opening the lid can cause a rapid loss of humidity during a sensitive stage of the hatch.

Days 19 to 21: Pipping and Hatching

As hatch day approaches, you may notice an egg rocking slightly or hear faint chirping from inside.

Eventually you may see a small crack or hole appear in the shell. This is called an external pip.

Do not panic if the chick does not hatch immediately after pipping. Hatching takes energy, and chicks normally alternate between working and resting.

After the first pip, the chick gradually works around the shell in a process known as zipping. Once enough of the shell has been opened, the chick pushes itself free.

Avoid opening the incubator or trying to remove the chick from its shell unless you have been specifically instructed to intervene.

After the Chick Hatches

A newly hatched chick will usually look wet and tired.

Leave the chick inside the incubator while it dries and becomes fluffy. The warm environment allows it to recover from the effort of hatching.

Once the chick is dry and ready to move to the brooder, make sure the brooder has:

• An appropriate heat source
• Chick starter feed
• Clean drinking water
• Fresh bedding
• Enough space for the chicks to move comfortably

With a Hatchables rental, the brooder equipment, feed, bedding and care supplies are already included with your kit.

What If the Eggs Do Not Hatch Exactly on Day 21?

Day 21 is an expected hatch date, not an exact deadline.

Some chicks may hatch slightly earlier or later depending on factors such as incubation conditions and natural variation.

If an egg has not hatched immediately on Day 21, avoid repeatedly opening the incubator or attempting to assist without guidance.

Hatchables customers can contact us for support if they are unsure what they are seeing during hatch day.

Hatch Chicks at Home or in the Classroom

Hatchables provides complete chick hatching experiences for families, schools, daycares and educators across Ontario.

Our chick hatching kits include fertilized eggs, an incubator, brooder equipment, feed, bedding, a candling light, educational resources and support throughout the experience.

Ready to start your own hatch? Explore our chick and duck hatching kits and choose an available rental date.