Assuming the egg in question is that of a chicken, the weight of the egg varies from approximately 1.25 oz on the low end to 2.5 oz at the high end. The weight of an egg depends on the type of bird that laid it as well as the precise size of the egg.
Chicken eggs are classified based on their sizes. A jumbo egg weighs about 2.5 oz, an extra large egg weighs approximately 2.25 oz and a large egg weighs about 2 oz. A medium chicken egg clocks in at about 1.75 oz, while a small egg weighs in at 1.5 oz. The rarely found pee-wee chicken egg weighs 1.25 oz. Most recipes call for the use of a large egg.