Top Five Chicken Breeds That Produce the Largest Eggs :
According to Henderson's Chicken Breed Chart, there are at least a dozen chicken breeds that produce large eggs. The chart lumps together large, extra large and jumbo into its "large" classification. There is also variation among hens of a breed, depending on their health and age. The older and healthier a hen is, the larger her eggs usually are. Egg sizes are jumbo, extra large, large, medium, small and tiny. Extra large, large and medium are the most common sizes available. Since one person's "jumbo" can be another person's "large," sizes are classified by the net weight in grams or ounces of a dozen eggs. Across the United States, the average weight of a single large egg is 5 grams (2.1 ounces). Whereas it takes 5 large eggs to make a cup, it only takes 4 jumbo or extra large eggs.
It is generally agreed among producers that the following five breeds are the best for producing the largest eggs.
Barnevelder - Developed in Holland in the late 1800s, the Barnevelder is famous for its very dark brown, jumbo-sized eggs. This is a dual-purpose meat/layer breed, and the chicks are slow to mature.
Red Star Sexlink - The Murray McMurray Hatchery and other hatcheries market a number of sexlink chicken varieties. Although the McMurray website describes the brown eggs as large, according to several producer testimonials, the Red Star Sexlink can produce extra large to jumbo eggs.
Rhode Island Red - Developed in New England in the 1800s, the Rhode Island Red gets the vote across the board for consistently laying large to extra large brown eggs. It is a hardy breed and adapts well to confinement or free range.
Commercial Leghorn - The leghorn is one of the most popular breeds in the world. As a historic breed it is a good egg producer. But the specially bred commercial varieties now available are egg "factories." They are hardy and they mature earlier than most breeds. Their white eggs are large to extra large, and they are thrifty in converting feed to egg production.
Delaware - This rare breed was developed in Delaware in 1940. It is hardy, calm and matures early. The hens lay large to extra large brown eggs.
There are several qualified runners up in the "biggest egg" debate. The Plymouth Rock, Andalusian, Chantecler, Minorca, New Hampshire, Welsummer, and Wyandotte are all listed by Henderson's Chicken Breed Chart as producing large eggs. Some producers report their Turkens (also called Naked Necks) lay the largest eggs of any of their chickens.
References: Henderson's Chicken Breed Chart; Blogs and testimonials by chicken hobbyists; Murray McMurray Hatchery website; Ideal Poultry website; Learn More About Eggs website.