Why didn’t my eggs hatch?

Generally, chicken eggs hatch after approximately 21 days of incubation at optimal temperature. If your eggs have not hatched by Day 24, it is safe to assume they will never hatch. There are several common causes why the eggs fail to hatch:

Egg quality

Remember that a healthy egg can only come from healthy, nourished breeding pairs (of course, you’ll need a rooster to get fertile eggs). What you feed your chickens impacts the eggs they produce. The quality of life you give them is also important. As the old adage goes, you reap what you sow.

If you’re buying fertile eggs whether from eBay seller or locally, just make sure you do your due diligence that the seller is worthy of buying from.

Infertile eggs

It’s very natural that not every egg that a chicken lays is fertilized or viable. Only some are. That is why candling your eggs after the first week is a good idea so you can remove those that are not developing.

Improper care or mishandling of eggs prior to incubation

The hatchability of eggs can be severely reduced by improper care prior to incubation. A fertile egg contains live cells that can become a viable embryo and then a chick. It is so delicate that it can be ruined by small mistakes. This is particularly a risk with shipped eggs, for a multitude of reasons, such as rough handling, including accidental mishandling (dropped, crushed, jostled, etc.), intentional mishandling by post office or transportation company personnel (someone having a bad day), extreme temperature fluctuations on the ground and in flight, air pressure issues in flight, X-rays, etc. So you just have to assume your hatch rate is going to be lower with shipped eggs. And sometimes you’ll be pleasantly surprised.

If you are using your own fertile eggs, the eggs must be collected carefully and stored properly until they are incubated. Fertile eggs should be stored in a clean, sterile plastic egg carton or plastic storage box with their pointed ends facing downward. The best storing conditions are in an area that is 53–70°F (11.6–21°C) depending on the expected length of storage time, with a humidity level around 70–80% (see ‘Eggs too old when set’ below). The cool temperature will delay embryonic growth until incubation begins, and the high humidity will keep the eggs from drying out. Ideally, eggs should not be more than 7 days old when they are set (placed in an incubator). Beyond that point, the hatchability of eggs will drop 0.5–1.5% per day with the percentage increasing as storage extends further. After 2 weeks of storage, the chick quality will also be impaired. To learn more about storing fertile chicken eggs correctly, check out this article by Catherine Andrews of Raising Happy Chickens.

Improper temperature levels or humidity levels

It is important to remember that chicken eggs need to be kept in a controlled environment for 21 days to insure a healthy hatch. Even a fluctuation of one degree higher or lower over an hour or two can kill the embryo inside or cause abnormalities in the developing chick. Sometimes, too low of an average temperature can also delay the hatch. Too high a temperature, then may just lead to an early hatch.

The temperature in the incubator should hover around:

  • 99–99.5°F (37–37.5°C) in a forced-air incubator
  • 101–102°F (38– 39°C) in a still-air incubator

Read more: What is the difference between forced/circulated-air incubator and still-air incubator, and what are the pros and cons of each?

Dirty and contaminated eggs

There are two problems with dirty eggs. First, a typical 60g chicken egg has about 10,000 pores (Schmidt–Nielsen, 1984), which allow the diffusion of air. So, since the egg shell is permeable, it would be dangerous for the embryo to develop inside of a shell that is covered with dirt or muck.

(Source: North Carolina Cooperative Extension Service)

The second issue is that bacteria can enter through the shell pores and grow in the protein-rich environment inside the shell, and even potentially contaminate the incubator interior part and other eggs. And thus kill the growing embryos. The average eggshell pore diameter is about 17 μm (microns) (0.017 mm) (Wangensteen et al., 1971), and most bacteria range from 0.2–2.0 µm (microns) in diameter (Microbiology, An Introduction. California: Tortura, Funke, Case, 1998). Hundreds of thousands of bacteria can fit through the pores.

So, make sure that none of the eggs are cracked and that they are all clean, and it’s advisable not to wash them with water. When a hen lays an egg, the egg is coated with a protective layer (about 1μm in thickness) called the cuticle, sometimes called the bloom. Washing and sanitizing can remove the cuticle on the egg making the egg even more vulnerable to contamination from bacteria.

Even with good flock management, somehow some eggs will get dirty. This guide here will help you on how to correctly clean eggs for incubation.

That is why it’s just a good idea to purchase hatching eggs and/or chicks only from NPIP breeders. NPIP stands for National Poultry Improvement Plan, and it’s a voluntary certification system that poultry breeders and hatcheries can participate in. However, today, NPIP is required for those that plan to move birds and/or eggs across state lines for the purposes of sales or shows. Flocks with NPIP certification have been regularly tested for Fowl Typhoid and Salmonella Pullorum that can be passed from a mother hen through the egg to a chick.

For more information on NPIP, please click here.

If you are interested in having your flock certified, or want more information on how to get NPIP certified in your state, you’ll need to contact your local office. A list of state representatives can be found here.

Insufficient rotation of the eggs

In nature, a broody mother hen will turn her eggs over 50 times per day. In artificial incubation, you must replicate this by either using an incubator that comes with an automatic egg turner or by turning the eggs manually by hand. Make sure your hands are clean to avoid passing bacteria and dirt to the eggs (see ‘Dirty and contaminated eggs’ above). Eggs should be rotated at least 3 times a day, and 5–7 times is even better. An auto turner will normally turn (or rock) the eggs 6 times per day. The result of incomplete or insufficient egg rotation is that chick organs stick to the sides of the shells. Chicks are born with their intestines outside their bodies. Stop turning the eggs during the last 3 days of incubation and at the same time as you increase the humidity in the incubator to between 65–70%.

Eggs too old when set

Eggs should ideally be incubated as soon as possible once laid. Hatchability decreases under even optimum conditions of eggs stored more than one week. However, it is often necessary to store eggs prior to incubation. A homesteading mommy Anna Merhalski of saltinmycoffee.com came up with a chart to help other chicken keepers determine the optimal storage temperature based on expected length of storage.

(The above photo is the property of Anna Merhalski of saltinmycoffee.com.)

A specific humidity level must be maintained to prevent moisture loss of the eggs. The ideal humidity level for hatching eggs is still being debated among experts, but many agree that it should at 75% for storage of eggs less than 7 days, and 80% for eggs stored more than 7 days.

It is also advisable to turn the position of the eggs 1–2 times per day during storage.

It is important that after refrigeration, allow cool eggs to pre-warm slowly to room temperature or ideally 75–80°F (24°C–27°C) over a period of 6–12 hours before placing in the incubator. Abrupt warming from 53–64°F (12–18°C) up to 99–102°F (37–39°C) causes temperature shock to the embryo and moisture condensation on the eggshell (Hodgetts, 1999), which leads to disease and reduced hatch rates.

Improper incubator ventilation, oxygen starvation

As described in the ‘Dirty and contaminated eggs’ above, the embryos inside the eggs need oxygen to grow. If the incubator is poorly ventilated, the oxygen supply will be exhausted and the chicks will suffocate.

Most incubators have been designed to ensure enough oxygen to come in and to allow the produced carbon dioxide and evaporated water to escape. Be sure to follow the manufacturer’s instructions regarding how to use the vent holes in your incubator.

Faulty incubator

Keep in mind that no incubator is completely perfect. An incubator that employs good management of the temperature, humidity, egg turning, and ventilation can expect a 60–80% hatching rate. It is rare to achieve over 80%; commercial operations may get up to a 90%.

It is also important to understand that even the best incubator, just like any equipment, has a chance of failing.

It is amazing just how many stories we’ve read and heard of incubators failing after just a few weeks of use, which can be absolutely heartbreaking — especially if you have paid good money for the eggs. If you are running your new machine for the very first time, read over the manual first, and go through it to figure out what all the buttons and functions are for, and then run it up before ordering your eggs. This goes for all types of incubators, including high quality units such as Brinsea®. This way you can be sure your new machine works correctly before spending your hard earned money on eggs that can turn bad if a machine is faulty or you’re misusing it (eggs don’t remain fertile forever).

Unnoticed power outage

Sometimes an unnoticed power outage happens or even human error (bad electrical wiring in the house) that causes damage to power lines.

I read on the Brinsea website that in 1969, H. Lundy identified 5 temperature zones characterized by their effects on the developing embryo. These studies were carried out on chicken eggs in an artificially controlled environment, but we can look to them for some idea of how the eggs might respond to ambient temperature. The 5 zones are:

  1. The zone of heat injury or death: Above 104.9°F (40.5°C)

At continuous temperatures above 40.5°C (104.9°F) no embryos will hatch. If only a short period of high temperature is not necessarily lethal.

  1. The zone of hatching potential (optimal temperature): 84.5°F to 104.9°F (35°C to 40.5°C)

Within this range there is the possibility of eggs hatching. The best is 100.4°F (37.8°C).

  1. The zone of disproportionate development: 80.6°F to 95°F (27°C to 35°C)

Eggs left too long in this zone can cause uneven growth of the embryos inside the eggs, which in turn, lead to crippling injuries or death. Successful hatching is greatly reduced.

  1. The zone of suspended development: 28.4°F to 80.6°F (-2°C to 27°C)

Eggs at this temperature don’t develop at all. Freshly laid eggs can be stored at this temperature with no harm to the embryos.

  1. The zone of cold injury or death: Below 29°F (-2°C)

Below this temperature, ice crystals will start to form inside the egg and cause permanent damage to the internal structures.

In case of power failure, ensure that the eggs are as warm as possible until the power returns. Here are 4 ways you can do it:

  1. Insulate with a cardboard box

By placing a large cardboard box over the top of the incubator to create additional insulation can help keep the incubator warm. In extreme cold, covering the box with blankets may help. Then place lit candles under the box that covers the incubator to warm the eggs. Please be cautious not to cause a fire. The heat from the candles can easily keep the eggs above 90°F (32°C) until the power returns. Embryos have survived at temperatures below 90°F (32°C) for up to 18 hours. Candle the eggs 4–6 days after the outage to check whether they are still viable and if not, terminate incubation. A power outage usually delay hatching by a few days and decrease the hatchability to 40– 50%.

  1. Power inverter

You can use a power inverter and connect it to your car (via the cigarette lighter plug) or motorcycle battery, but you must ensure the engine is running to prevent battery damage. Or have a 12V battery specifically for your inverter. The advantage of connecting it directly to a battery is that you don’t have to keep your car or motorcycle running, which means it is better for the environment.

  1. UPS backup battery

UPS stands for ‘Uninterruptible Power Supply’. A UPS is typically used to provide backup power for computer servers, for example in data centers or telecommunications or in the lab environment to prevent data loss and interruptions to must-run operations, and allow controlled shutdown of connected equipment when utility power fails. There are different UPS models with different power storage capacities, run times (several minutes to several hours) and different prices. You need to read the specifications of the UPS and the power consumption of the total load of your incubator. UPS with a greater battery capacity will give greater runtime. Runtime is the time duration you want your batteries to backup for. Use this calculator to recommend a battery capacity based on the desired runtime when power goes out. For example, Brinsea Maxi II Advance Automatic 14-egg incubator specification says its maximum power consumption is 40 Watts, and the typical average is 24 Watts. Let’s say your desired backup runtime is 2–3 hours, so this APC 1000VA UPS Battery Backup (BX1000M) would fit the bill.

Unfortunately, UPS batteries will not last indefinitely. Normal battery life expectancy is 3–4 years; this is dependent on the frequency of use, duration of use and environmental conditions such as heat and humidity. It is a good idea to periodically test your UPS to ensure that it works when you need it.

  1. HotHands® Warmers

Essentially the most dangerous option. These air-activated disposable heat packets can last up to 10 hours upon activation with the average temperature ranges from 126–144°F (52–62°C) — way too hot for the eggs! I don’t have experience with this, but I’ve read that people put the heat packets in the bottom of the incubator. Remember though, if you choose to use this desperate measure, be sure to keep a close eye on the temperatures, never allowing your eggs to get too warm or too near to the pads.

Placing the incubator at the wrong location

Not every space is going to be a good fit for the job. The incubator should not be placed in drafty areas, near open windows, air conditioning unit, heating vents, or heat-generating equipment since fluctuating temperatures may affect the incubator temperature. The incubator should be in a room with a fairly stable temperature between 70–75°F (21–24°C). Also, be sure that the incubation room offers generous fresh air ventilation.

Note: For a beginner, it is recommended as a prudent way of familiarizing with the basic techniques that you hatch with a small quantity of inexpensive eggs before attempting to hatch large quantities of eggs or expensive eggs.


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