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Tips for Hatching Chicken Eggs in an Incubator

Starting a backyard flock with a small incubator and some hatching eggs can be fun and educational. How successful you are at hatching chicken eggs in an incubator will depend on a number of factors, some of which are out of your control — such as the inherent degree of difficulty in hatching eggs from your chosen breed. But how carefully you operate your incubator is fully within your control. These tips will help you get the best results when hatching chicken eggs in an incubator.


Clean Eggs

Hatching eggs need not be completely spotless. But extremely soiled eggs carry harmful bacteria and should never be put into an incubator. Any attempt to clean filthy eggs will only drive bacteria through the shell, reducing hatchability.


Slightly soiled eggs, however, may be cleaned with fine sandpaper or a dry sanding sponge, or wiped off with a damp cool cloth and then dried with a paper towel. Hatching eggs purchased from a reputable source should not require any cleaning.


Egg Position

The pointed end of each egg should remain lower than the large round end, letting the developing embryo properly orient for the hatch. Maintaining egg position is easier in an incubator with an egg rack, compared to one in which the eggs simply lie loose.


The eggs must be turned periodically throughout the day for the first 18 days of incubation. But opening the incubator to turn eggs by hand makes it difficult to regulate the incubator’s temperature and humidity. An automatic egg turner handily solves that problem.


Stop turning the eggs 3 days before they are scheduled to hatch. Remove the egg rack or turner, lay the eggs on their sides, and don’t touch or move them until they have completely hatched, and the chicks have dried.


Incubation Temperature

Most chicken egg incubators are factory preset at 99.5 to 100°F. Avoid adjusting the temperature setting. Only after you gain experience using a specific incubator should you attempt to improve your hatching rate by tweaking the temperature setting slightly up or down.


Several weeks before you’re ready to start hatching, turn on the incubator to checked it out. Make sure it runs properly for at least 2 days.


Expect the temperature to drop when you put the eggs in. It will gradually return to operating level as the eggs warm to proper temperature.


Incubation Humidity

Providing humidity during incubation prevents excess loss of natural moisture from within the eggs. The drier the air inside the incubator, the faster moisture will evaporate through the eggs’ shells. Conversely, moister air slows the rate of evaporation from the eggs. Too high or too low humidity can prevent chicks from emerging from the shell during the hatch, or cause abnormalities in those that do manage to hatch.


Optimum incubation temperature and humidity are interrelated. As the temperature goes up, relative humidity must go down to maintain the same hatching rate.


Small eggs laid by bantams and jungle fowl have a relatively large surface-to-volume ratio, so they evaporate more quickly than larger eggs. Similarly, late-summer eggs of any size have thinner shells because hens have been using up calcium reserves all summer. Eggs with thin shells evaporate more rapidly than early-season eggs.


Eggs that evaporate more quickly generally hatch better at a lower temperature and higher humidity than is normal. For example, an incubator that produces good hatches at a temperature of 99°F and relative humidity of 55% will do a better job of hatching small eggs, or those with thin shells, at a temperature of 98°F and relative humidity of 70%.


The requisite amount of humidity increases about 5% during the hatch. In nature the first chicks to hatch under a hen contribute to the needed extra humidity, thus assisting the later, and typically weaker, chicks to get free of their shells. An incubator operated at 55% relative humidity, for example, should have the humidity increased to 65% during the last 3 days of incubation.


Egg Candling

Whether you choose to candle the eggs or not is up to you. The main reason to candle incubated chicken eggs is to make room in the incubator for more eggs. However, if not done quickly, candling can interfere with the incubator’s temperature and humidity regulation.


A typical candling schedule is to candle after one week of incubation (when infertile eggs appear clear), after two weeks of incubation, and at the time turning is discontinued. Candling eggs once, after 10 days of incubation, is another common option.


In a darkened room, hold an egg against a bright light, such as that provided by a hand held egg candler, you can see what’s going on inside the shell. Eggs with colored shells are more difficult to candle than white-shelled eggs, and speckled eggs are most difficult of all. While you’re learning what to look for, images of embryo development inside the shell can be extremely helpful.


Egg Hatching

The eggs of most chicken breeds hatch after 21 days of incubation. Large eggs — such as those laid by Jersey Giants — can take as much as 2 days longer than normal, while smaller bantam eggs tend to hatch a day or two early. Eggs laid by the smallest bantam, the Serama, may take as little as 17 days to hatch.


Rarely will all the eggs in the incubator hatch. “Our large capacity incubators hatch eggs at 70 to 80%,” says Jeff Smith of Cackle Hatchery®. “A more typical hatch rate for small hobby-type incubators is 50 to 70%.”


With experience using a given incubator, and with fresh fertile eggs from healthy hens, you may get your hatch rate up as high as 85%, or occasionally even 100%. The best advice you can find on how to use your incubator is in the written directions that came with your particular model.


And that’s today’s news from the Cackle Coop.


Gail Damerow is the author of Hatching and Brooding Your Own Chicks

3 thoughts on “Tips for Hatching Chicken Eggs in an Incubator

  1. What are your thoughts on dry hatching? I have a really hard time keeping humidity under control and 7 of my babies grew completely and I think drowned in egg. Thanks

  2. Really well written, intelligent article. I like to remind myself of good practices before attempting a hatch.

  3. Very useful article.

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