There is a study in sexing eggs by shape.

[crb1487]

The study results can be read at the link below. However, just a warning... It gets very technical and may make your eyes roll to the back of your head.

In short, the results say, "Yes. You can determine chicken sexes by shape" with some 80ish percent accuracy.

Imagine the thousands of culled male chick's that could gave been saved from their terrible end if this method was used more and used correctly.
https://www.ncbi.nlm.nih.gov/pmc/ar...eral, eggs with a,index will be female chicks.

 

[Kiki]

In short, the results say, "Yes. You can determine chicken sexes by shape" with some 80ish percent accuracy.

 

[Obsessed With Silkies]

I don't think there's a for sure way to tell by a shape of an egg if it will be male or female. The size of eggs laid day to day will vary, thus the results can not be 100% accurate. Have you tried that hatch method before?

 

[Obsessed With Silkies]

Here's the link to thevsame question you are asking. It had a good amount of responses.
https://www.backyardchickens.com/threads/does-egg-shape-determine-gender.1515820/

 

[NatJ]

In short, the results say, "Yes. You can determine chicken sexes by shape" with some 80ish percent accuracy.

On a small sample size (60 eggs, 47 hatched.)

I think it is convincing enough that someone should try it with larger numbers of eggs. I am 100% confident it is not ready for commercial use yet.

 

[UncleChuck]

I read in a book published in the 1920s in which a chicken farmer details a method she claimed would produce 98% the desired sex by sorting eggs based on size, shape, and orientation of the air sac. She claimed that in larger eggs with a perpendicular air sac produced cockerels and medium eggs with an air sac positioned off center, in such a way that it can only be viewed from one side of the egg, would produce pullets. Most eggs fall somewhere in the middle and would be sent to market.