How to Incubate Chicken Eggs: Temperature, Humidity, Turning & Hatch Day

Hatching chicken eggs at home is not difficult because of one secret setting. It is difficult because several small things have to stay reasonably consistent for about three weeks.

You need fertile eggs in good condition, a properly prepared incubator, reliable temperature control, enough moisture without drowning the egg in humidity, regular turning, good ventilation and patience during the final hatch.

Chicken eggs normally take about 21 days to hatch. Mississippi State University Extension lists 21 days as the standard incubation period, although actual hatch timing can shift with temperature, egg storage and other conditions.

If this is your first flock, it is also worth planning beyond hatch day. BlogAgri’s Poultry Care for Beginners covers basic housing, water, feed, cleanliness and predator protection once the birds move beyond the incubator and brooder stages.

Quick Answer: For chicken eggs, Mississippi State University Extension recommends about 100°F (37.8°C) in a forced-air incubator and 102°F (38.9°C) in a still-air incubator. Turn eggs regularly through day 18, then stop turning for hatch. Humidity should support appropriate moisture loss from the egg rather than being treated as one universal percentage for every incubator and environment.

Start With Good Fertile Eggs

The incubator can provide warmth, moisture and ventilation, but it cannot correct poor fertility or badly damaged eggs.

Choose hatching eggs from a healthy breeding flock where hens have had access to a fertile rooster. Eggs should be reasonably fresh, clean, normally shaped and free from cracks.

University of Missouri Extension recommends selecting eggs with normal size, shape, color and shell texture while rejecting dirty, cracked or obviously defective eggs. It also notes that eggs hatch best when set relatively soon after laying.

A practical hatching egg should have:

• A sound shell
• Normal shape
• No cracks
• No obvious thin areas
• No heavy contamination
• Known or reasonably likely fertility
• Limited storage time

Do not assume the biggest egg in the nest is automatically the best hatching egg.

Very large, tiny or unusually shaped eggs can be poorer candidates for incubation.

Egg Selection Tip: Start with the best eggs you have. Incubation is much easier when you are not asking the machine to compensate for poor egg quality.

How to Store Hatching Eggs Before Incubation

If you collect eggs over several days, they need different storage conditions from ordinary table eggs.

University of Maine Cooperative Extension recommends storing hatching eggs large end up at about 50–60°F (10–16°C) with relative humidity around 75%. It recommends setting them within roughly 7–10 days, because hatchability declines as storage becomes prolonged.

University of Missouri Extension gives a similar principle, recommending cool storage around 45–55°F with approximately 70–75% humidity.

The exact numbers differ slightly between Extension references, but the lesson is the same:

Keep fertile eggs cool, humid and stable rather than warm, dry or exposed to big temperature swings.

If eggs are stored longer than about a week, University of Maine recommends changing their angle or turning them daily.

Before putting cool eggs into a warm incubator, allow them to warm gradually. Sudden warming can produce condensation on the shell, which may encourage microbial contamination.

Do Not Use an Uncontrolled Cardboard-Box Heat Setup

A cardboard box with a light bulb beside it may sound simple, but it is not a dependable incubation system.

Chicken embryos need reasonably controlled temperature, moisture and ventilation for almost three weeks. An uncontrolled heat source can produce dangerous hot spots and unstable temperatures.

Mississippi State does publish designs for home-built incubators, but these are actual incubator designs with controlled heat, ventilation, insulation and thermometer placement—not simply a cardboard box placed beside a lamp.

For most beginners, use a purpose-built incubator with:

• Thermostatic temperature control
• Reliable thermometer
• Ventilation openings
• Humidity/water system
• Manual or automatic turning
• Enough room around the eggs for airflow

If you build your own incubator, use a tested Extension design and safe electrical components.

Prepare the Incubator Before the Eggs Go In

Do not switch on the incubator and immediately fill it with eggs.

Run it first.

Mississippi State recommends starting an incubator a day or two before setting eggs so temperature, water and other conditions can stabilize. It also recommends cleaning and disinfecting the incubator before use.

During this test period, check:

• Temperature stability
• Thermometer accuracy
• Humidity response
• Turner operation
• Ventilation
• Water reservoirs
• Room temperature
• Whether sunlight hits the incubator
• Whether the machine develops hot or cool areas

This is also the time to read the incubator manufacturer’s manual.

Do not wait until valuable eggs are inside to discover that the turner is not moving or the thermometer reads inaccurately.

Before You Set Eggs: The goal is a stable incubator before day 1, not constant adjustment after development has started.

Forced-Air vs Still-Air Incubator Temperature

This is one of the most important things to get right.

A forced-air incubator has a fan that circulates warm air.

A still-air incubator does not.

Because heat forms layers inside a still-air machine, the two incubator types are normally operated at different temperature readings.

Mississippi State University Extension recommends the following chicken-egg settings.

In a still-air incubator, thermometer position is particularly important. Mississippi State recommends measuring around the top level of the eggs rather than near the floor of the incubator.

University of Maine gives slightly different working values—around 99.5°F for forced-draft incubators and 101.5°F for still-air machines.

That difference between reputable Extension references is useful.

It tells us not to mix settings from different machines and different manuals.

Practical Rule: Know your incubator type first. Then follow the manufacturer guidance and an appropriate poultry Extension reference rather than copying a random temperature from another keeper’s machine.

Temperature Consistency Matters

Small, brief air-temperature fluctuations are not the same as operating the incubator at the wrong temperature for hours or days.

Mississippi State notes that prolonged high temperature can cause early hatches and reduce hatchability, while consistently low temperature can produce delayed hatches.

The developing egg changes temperature more slowly than the air around it, which is why you should avoid constantly turning the thermostat up and down in response to tiny display changes.

Keep the incubator away from:

• Direct sunlight
• Heating vents
• Drafty windows
• Cold exterior walls
• Rooms with large day/night temperature swings

Also check the thermometer itself.

Mississippi State warns that even a persistent one-degree thermometer error over the incubation period can interfere with embryo development.

Humidity Is About Moisture Loss From the Egg

Humidity causes more confusion than almost any other part of incubation.

One article says 45%.

Another says 55%.

Another says 65%.

The reason is that incubator design, room humidity, ventilation, eggshell characteristics and measurement methods can all affect how quickly the egg loses water.

Mississippi State gives about 58–60% relative humidity during the first 18 days, then 65% or more during hatch as a reference.

However, the more important biological target is appropriate water loss from the egg.

Mississippi State describes about 12% egg-weight loss during incubation as desirable. Its guidance also explains that humidity that remains too high can prevent enough water from leaving the egg.

Humidity Reality Check: Do not chase one percentage just because somebody else’s incubator worked at that number. Watch how your eggs are losing moisture.

Use the Air Cell to Monitor Moisture Loss

As an egg loses moisture during incubation, the air cell at the large end becomes larger.

Candling lets you see that air-cell development.

Mississippi State’s avian embryo guidance uses days 7, 14 and 18 as useful reference points when evaluating air-cell development.

If the air cell is much smaller than expected, the eggs may not be losing enough water.

If it becomes unusually large too quickly, the eggs may be losing moisture too rapidly.

The adjustment usually involves humidity, but always remember that ventilation and incubator design also influence moisture loss.

For more precise monitoring, some keepers weigh groups of eggs.

The basic calculation is:

Egg weight loss (%) = (starting weight − current weight) ÷ starting weight × 100

For example:

Starting tray weight = 600 g
Current tray weight = 528 g

Loss = 72 g

72 ÷ 600 × 100 = 12%

That gives you a much more meaningful picture than staring at the hygrometer alone.

Ventilation Is Essential

A developing embryo is alive and exchanging gases through the shell.

Oxygen enters while carbon dioxide leaves.

As the embryo grows, its oxygen requirement increases. Mississippi State recommends gradually increasing ventilation and emphasizes that unobstructed vent openings are essential, particularly near hatch.

Do not close incubator vents in an attempt to force humidity higher.

Mississippi State specifically warns that air exchange demand is greatest near hatch and that closing vents to raise humidity can deprive the chicks of oxygen.

Hatch-Day Rule: Increase humidity using the incubator’s water system or exposed water surface—not by starving the embryos of fresh air.

How Often Should Chicken Eggs Be Turned?

Chicken eggs need regular turning during most of incubation.

Mississippi State recommends turning them at least 4–6 times per day and stopping during the final three days before hatch.

Automatic turners make this simple.

If turning by hand, an odd number such as five turns per day is convenient because the eggs do not spend every night resting on the same side.

You can mark the shell lightly with pencil:

X on one side
O on the other

That makes it easy to see which eggs have already been turned.

Turn eggs gently.

Developing embryos have delicate blood vessels, particularly during early incubation, so avoid shaking or rough handling.

Which End of the Egg Goes Up?

If eggs are placed vertically in a rack, set them with the large end up and small end down.

If the incubator is designed for horizontal eggs, they can lie on their side with the large end slightly elevated.

Mississippi State specifically advises against setting eggs with the small end upward because correct orientation helps the embryo move into the proper position for hatch.

When to Candle Chicken Eggs

You do not need to candle eggs every day.

In fact, constant handling adds disturbance without providing much additional value.

Useful checkpoints are around:

Day 7

You may see blood vessels and early embryo development.

Clear eggs may be infertile, although dark shells can be difficult for beginners to interpret.

Day 14

The embryo occupies much more of the egg and the air cell should be larger.

This is another good time to compare moisture loss.

Day 18

Make your final development and air-cell check before preparing for hatch.

Mississippi State uses days 7, 14 and 18 as reference stages when illustrating air-cell development.

Keep candling sessions short.

If an egg is cracked, leaking, heavily contaminated or obviously spoiled, remove it carefully.

University of Missouri Extension notes that damaged or contaminated eggs can support microbial growth and create problems within the incubator.

A Simple 21-Day Chicken Egg Incubation Schedule

Chicken eggs normally hatch around day 21.

Do not panic if every chick does not hatch at exactly the same hour.

Hatch timing can shift with incubation temperature, egg age and differences among individual embryos.

What Does “Lockdown” Mean?

Backyard poultry keepers commonly call the last three days lockdown.

For chicken eggs, that begins at approximately day 18.

At that point:

• Stop turning
• Remove or disable the egg turner if required
• Increase humidity to the incubator’s hatch setting
• Maintain strong ventilation
• Avoid unnecessary candling
• Avoid unnecessary opening
• Let chicks move into their hatch position

Mississippi State recommends stopping turning during the final three days and keeping the incubator closed as hatch begins.

The word “lockdown” is informal, but the management change is important.

What Happens During Hatching?

Before you see a crack in the shell, the chick normally enters the air cell and begins the final stages of hatch.

Eventually it makes an external hole through the shell. This is called pipping.

After pipping, a chick may rest for a substantial period.

That rest is normal.

The chick still has developmental work happening inside the shell and does not need to be pulled out simply because it is not moving continuously.

Mississippi State notes that improper humidity and poor ventilation are major reasons that chicks may reach the pipping stage but fail to complete hatch.

Avoid Repeatedly Opening the Incubator During Hatch

Once chicks begin pipping, humidity around the membranes becomes important.

Mississippi State explains that when humidity drops after a chick has pipped, shell membranes can dry and stick to the chick, making it harder for the bird to rotate and complete the hatch.

That is why you should not keep opening the lid every few minutes to see what is happening.

It may be tempting, especially during a first hatch.

Watch through the window instead.

Should You Help a Chick Out of the Shell?

Usually, patience is the safer first approach.

A chick may pip and then rest for many hours.

Helping too early can interfere with blood vessels that have not finished shutting down or with normal absorption of remaining yolk.

If several chicks repeatedly reach the same stage and fail to hatch, investigate the incubation process rather than assuming each chick needs manual assistance.

Check:

• Incubation temperature
• Hatch humidity
• Ventilation
• Egg orientation
• Turning history
• Egg storage
• Breeder flock condition

Mississippi State’s incubation troubleshooting guide links different failure patterns with specific possible causes rather than treating every unsuccessful hatch as one problem.

What to Do When a Chick Hatches

A freshly hatched chick is wet and tired.

Do not move it straight into a cool container.

Allow it to stay in the warm incubator until it has dried and fluffed.

Meanwhile, the brooder should already be prepared.

BlogAgri’s Chicken Brooder: A Guide to Raise Healthy Chicks explains the basic brooder setup for young chicks. The current BlogAgri archive lists this guide as part of the site’s livestock resources.

The brooder should be ready before hatch day with:

• Appropriate heat
• Dry bedding
• Clean chick-safe waterer
• Chick starter feed
• Enough room for chicks to move away from the heat
• Protection from drafts
• Good ventilation without chilling

Once chicks are eating regularly, BlogAgri’s Poultry Feed Calculator can help estimate total feed needs, bags and cost for a known flock size and feeding period.

Clean the Incubator After the Hatch

Do not store the incubator full of shell pieces, fluff and dried hatch debris.

Clean it promptly after the chicks have been removed.

Mississippi State recommends cleaning and disinfecting incubation equipment between batches because sanitation problems can contribute to poor hatch results and disease risk.

Follow the manufacturer’s cleaning instructions.

Remove detachable trays and water containers where appropriate.

Keep electrical components dry unless the manufacturer specifically says they can be washed.

Then allow everything to dry thoroughly before storage.

Why Chicken Eggs Fail to Hatch

A poor hatch does not automatically mean the incubator was at fault.

Some eggs may have been infertile from the beginning.

Others may suffer from breeder flock problems, poor storage, contamination, shell defects or embryo weakness before incubation even starts.

Mississippi State’s troubleshooting guidance lists numerous possible causes of incubation failure, including breeder nutrition and fertility, improper egg storage, temperature errors, turning problems, ventilation problems and incorrect humidity.

The pattern of failure usually tells you more than the final hatch percentage alone.

Clear eggs during candling

Possible causes include infertility or very early embryo death.

If many eggs are clear across several hatches, investigate breeder fertility as well as incubation management.

Blood rings or early embryo death

Possible causes include improper storage, incubation temperature problems, breeder nutrition or contamination.

Chicks hatch too early

A consistently early hatch may indicate that the average incubator temperature has been too high.

Chicks hatch late

A consistently late hatch can indicate low average incubation temperature, old eggs or temperature variation inside the incubator.

Sticky embryos

Mississippi State associates sticky embryos with problems including excessive average incubation humidity, low temperature and inadequate ventilation.

Fully developed chicks pip but do not hatch

Check both humidity and ventilation.

Mississippi State specifically identifies these as common reasons for failure at the pipping stage.

Troubleshooting Tip: Keep a notebook for every hatch. Record egg source, storage time, incubator type, temperature, humidity, turning, candling observations and hatch timing. Patterns become much easier to spot after several batches.

Common Chicken Egg Incubation Mistakes

Using the wrong temperature for the incubator type

Still-air and forced-air machines do not use identical temperature readings.

Trusting an inaccurate thermometer

Check equipment before setting eggs.

Storing fertile eggs too warm or too long

Hatching eggs should be held cool and incubated relatively soon after laying.

Treating humidity as one magic number

Use incubator guidance together with air-cell development and egg moisture loss.

Forgetting to turn eggs

Eggs need regular turning during most of incubation.

Continuing to turn after day 18

Stop turning during the final three days.

Closing vents to raise humidity

This can restrict the oxygen needed by late-stage embryos.

Opening the incubator constantly during hatch

Humidity can fall rapidly around pipped eggs.

Expecting every fertile egg to hatch

Even well-managed incubation does not guarantee that every embryo survives.

A Practical Incubation Checklist

Before setting eggs:

• Source fertile eggs
• Reject cracked or badly misshapen eggs
• Store eggs properly
• Clean the incubator
• Check thermometer accuracy
• Run the incubator before setting
• Confirm whether it is forced-air or still-air
• Test the egg turner
• Prepare a hatch record sheet

During days 1–17:

• Maintain appropriate temperature
• Turn eggs regularly
• Maintain ventilation
• Monitor humidity
• Candle around days 7 and 14
• Check air-cell development

On day 18:

• Candle one final time if needed
• Stop turning
• Prepare for hatch
• Increase humidity appropriately
• Keep ventilation open

During hatch:

• Avoid unnecessary opening
• Give chicks time
• Watch for general hatch patterns rather than one slow chick
• Keep the brooder ready

After hatch:

• Move dry chicks to the brooder
• Remove debris
• Clean and disinfect the incubator
• Record the results

FAQs About Incubating Chicken Eggs

For the next stage, see BlogAgri’s Chicken Brooder Guide.

Final Thoughts

Chicken egg incubation becomes much easier when you stop looking for tricks and start watching the basics.

Use good fertile eggs.

Know whether your incubator is forced-air or still-air.

Check the thermometer before the eggs go in.

Turn consistently during the first 18 days, watch air-cell development instead of chasing a random humidity number and keep the vents open as the chicks approach hatch.

Then, when the shells start pipping, give the chicks time.

A good incubation guide should help you understand what the embryo needs. It should not promise an “impressive hatch rate” or tell you success is guaranteed.

Keep records from each batch, learn from the pattern and improve the setup the next time.

Sources and Further Reading

• Mississippi State University Extension — Important Incubation Factors — temperature, humidity, ventilation, egg orientation and turning.
• University of Missouri Extension — Small Flock Series: Incubation of Poultry — egg selection, storage, embryonic development and incubation management.
• University of Maine Cooperative Extension — Hatching Your Own Chicks — egg storage, incubation preparation and hatch management.
• Mississippi State University Extension — The Avian Embryo — sanitation, thermometer accuracy, humidity, candling and air-cell development.
• Mississippi State University Extension — Pipped Eggs That Do Not Hatch — hatch humidity, ventilation and egg moisture loss.
• Mississippi State University Extension — Troubleshooting Failures With Egg Incubation — common hatch-failure patterns and possible causes.