The answer to whether a refrigerated egg can be incubated is generally no, especially for eggs purchased from a standard grocery store. Incubation requires the correct temperature, humidity, and ventilation to allow a fertilized egg to develop into a viable chick. Standard refrigeration temperatures, typically set near 40°F (4°C), are far too cold for successful embryonic development. This low temperature creates two significant barriers that prevent the egg from ever reaching the hatching stage.
The Essential Prerequisite: Are the Eggs Fertile
The most common reason a refrigerated egg will not hatch is that it is not fertile. Most commercially sold eggs, including those labeled as free-range or organic, are produced by hens kept separate from roosters. Hens naturally lay eggs regardless of mating, and these eggs are unfertilized ova containing no embryo to develop.
The large-scale commercial egg industry is not designed to produce chicks, so there is no financial incentive to house roosters, which require feed and space without contributing to egg production. Therefore, the vast majority of eggs found in a supermarket are infertile. The only eggs that can potentially be fertile are those sourced directly from a small farm or backyard flock where a rooster is actively present.
In a fertile egg, the germinal disc, the small white spot on the yolk, will appear larger and resemble a bullseye because cell division began before the egg was laid. Conversely, an infertile egg’s germinal disc will look like a solid, small white spot. If an egg is infertile, no amount of ideal incubation can cause it to hatch.
The Biological Impact of Cold Storage
Even assuming an egg is fertile, the standard refrigeration temperature of 40°F (4°C) causes irreversible damage to the developing embryo. This relates to the “physiological zero” (PZ), which is the temperature below which the embryo’s cellular activity is arrested but remains viable. For chicken eggs, the PZ is around 70°F (21°C), though optimal storage is often cited between 53°F to 60°F (12°C to 16°C).
When a fertile egg is placed in a refrigerator at 40°F (4°C), the temperature drops significantly below this physiological zero. The extreme cold causes the blastoderm—the early embryo—to suffer cellular damage and metabolic shock. Storing eggs at such a low temperature for more than a few days significantly reduces, or completely eliminates, the viability of the embryo.
The combination of low temperature and the dry environment of a refrigerator causes the embryo to lose structure and health. This damage prevents the embryo from resuming development when later placed in an incubator, drastically reducing the hatch rate, often to near zero.
Optimal Storage Conditions for Hatching Success
For those who possess fertile eggs and need to store them temporarily before incubation, the correct conditions contrast sharply with refrigeration. The goal of pre-incubation storage is to maintain the embryo in a state of suspended animation, above the temperature that causes cellular damage and below the temperature that initiates development. The ideal storage temperature range is between 55°F and 65°F (12°C and 18°C).
This temperature range keeps the embryo dormant but healthy, preventing rapid cell deterioration. High humidity is also necessary to prevent excessive moisture loss through the eggshell’s pores, which reduces hatchability. A relative humidity of 75% to 85% is recommended for storage.
Eggs should be stored with the large end facing upward because this is where the air cell is located, helping to keep the yolk and embryo correctly suspended. Hatchability begins to decline noticeably after seven days of storage, so eggs should ideally be set in the incubator within this timeframe. If storage must extend longer, up to ten days, the eggs should be gently turned once daily to prevent the yolk from sticking to the shell membrane.