Different Rates

Josie Chang | Her Chickies

April 3rd, 2025

When it comes to hatching eggs, there are four main rates that are important to know and distinguish. Understanding the difference between them can help you gauge how well your hatches will go—whether using your own eggs or purchasing from a breeder.

Fertility Rate

Fertility rate depends on the reproductive health of both the hen and the rooster. A fertile hen will consistently lay high-quality eggs—thick, uniform shell and a weight and size that align with her breed. A fertile rooster, on the other hand, should be able to cover multiple hens regularly with minimal effort. In my opinion, a fertile cock should cover at least three hens and an extremely fertile one should handle a group of up to 20.

There are two main ways to check for fertility:

1. Crack the egg open and look for a bullseye.
   1. An unfertilized egg will show a single, solid white dot on the yolk—no rings, no bullseye. That dot is the germinal disc or otherwise known as the blastodisc.
   2. A fertilized egg will show a dot that has a circle around it. This is called the blastoderm, but also commonly known as a bullseye.
2. Incubate the egg and check for development after 6+ days.
    

The first method means the egg can’t be incubated, and the second doesn’t account for fertilized eggs that fail to develop. Prolonged heat from incubation can also dissolve the germinal disc, so you won’t be able to check for a bullseye afterward.

Example:
If you crack open 10 eggs and 8 show a bullseye, your fertility rate is 80%.

Development Rate

Development rate refers to how many fertilized eggs actually begin to grow embryos. You can sometimes spot development by Day 3 of incubation, but typically Day 6 is the easiest—look for veins and visible growth inside the egg when candling.

Development rate is dependent on fertilized eggs, but there's no accurate way to check for fertilization without either cracking the egg or incubating it. So in practice, you’re measuring how many of your incubated eggs show signs of growth out of how many eggs you put into the incubator.

Example:
If you incubate 10 eggs and 7 of them develop veins and embryos, your development rate is 70%.

Hatch Rate

Hatch rate is the number of chicks that fully hatch from the eggs—meaning they make it through pipping, unzipping, and emerging from the shell. Hatch rate is directly dependent on the development rate, not the initial number of eggs.

Example:
If 10 eggs developed but only 6 hatched, your hatch rate is 60%.

Chick Survival Rate

Chick survival rate tracks how many chicks survive the first two weeks after hatching. While we often assume that chicks who successfully hatch will thrive, that’s not always the case.

Example:

If 100 chicks successfully hatch, but 20 fail to thrive and pass away, there is an 80% chick survival rate.

Closing Notes

While there’s no way to guarantee all of these rates when human error is involved, reputable and ethical breeders can reliably track and stand behind these rates within their own flocks. There’s no reason for breeders to charge more for hatching eggs if their rates are extremely low or non-existent. If a breeder can't do something as simple as this, they should sell eating eggs and not hatching eggs.

That being said, fertility can be guaranteed—it’s the easiest of the four to verify. If a buyer cracks open fresh eggs that have never been incubated and finds that none are fertilized (no bullseyes present), then the breeder is at fault for selling hatching eggs that were never going to hatch in the first place. While I hope my buyers wouldn't do this since I want them to hatch some fat babies instead of possibly wasting eggs, I would still accept that it is my responsibility to guarantee fertility rates for hatching eggs from my birds.

However, we handle this process ourselves to ensure that buyers never feel the need to crack open our eggs to check for fertility. At Her Chickies, we are super transparent about our fertility rates! We post monthly updates and only sell hatching eggs from pens that consistently show 70% or higher fertility. We firmly believe that charging a premium price for hatching eggs means committing to guaranteed fertility (70+%) and doing everything we can to provide the best possible outcomes for anyone who purchases from us.

That means we’re always hatching, always cracking open eggs, and always following up with our customers. We feed our birds a diet that meets all their nutritional needs, provide quality supplements, and make sure they’re as healthy, spoiled, and well-loved as possible. 

Happy, healthy breeders means happy, healthy offspring.

This does not mean that we guarantee development, hatch and/or chick survival rates outside of our own. There are just way too many factors that can impact these rates and all of them are entirely out of our control. In regards to these three, we can only be transparent about our own personal rates when asked. It is the very least we can do!  ｡^‿^｡  ♡