Quote:Chicken eggs are graded by size, for the purpose of sales. The weight of an egg minus the shell is about 13% less than the weight of the egg including the shell.

United States of America
The United States Department of Agriculture sizing is based by weight per dozen.[1] The most common US size of chicken egg is 'Large' and is the egg size commonly referred to for recipes.

The following egg masses have been calculated on the basis of the USDA sizing:

Modern Sizes (USA)
Size                                        Mass per egg                      Cooking Yield (Volume)[2]
Jumbo                                Greater than 2.5 oz. or 71 g
Very Large or Extra-Large (XL) Greater than 2.25 oz. or 64 g       56 mL (4 tbsp)
Large (L)                                Greater than 2 oz. or 57 g       46 mL (3.25 tbsp)
Medium (M)                                Greater than 1.75 oz. or 50 g       43 mL (3 tbsp)
Small (S)                                Greater than 1.5 oz. or 43 g
Peewee                                Greater than 1.25 oz. or 35 g

Canada
In Canada, modern egg sizes are defined as follows:

Modern Sizes (Canada)
Size              Mass per egg
Jumbo      70 g or more
Extra Large      63-69 g
Large              56-62 g
Medium      49-55 g
Small              42-48 g
Peewee      Less than 41 g

Europe
In Europe, modern egg sizes are defined as follows.

Size          Mass per egg
Very large  73 g and over
Large          63-73 g
Medium  53-63 g
Small          53 g and under

Australia
In Australia, the Australian Egg Corporation defines the following sizes in its labeling guide.[5]

Modern Sizes (Australia)
Size        Mass per egg
King‐size 70.0g – 78.0g
Jumbo 66.7g – 70.0g
Extra-Large 58.3g – 66.6g
Large        50.0g – 58.2g
Medium 42.0g – 49.9g

In Western Australia, two additional sizes are also standardized by the Golden Eggs Corporation

Additional Sizes (Western Australia)
Mega or XXXL 72 g
Medium        43 g

New Zealand
In New Zealand sizes are based on the minimum mass per egg:

Modern Sizes (New Zealand)
Size        Minimum mass per egg
8 (Jumbo) 68 g
7 (Large) 62 g
6 (Standard) 53 g
5 (Medium) 44 g
4 (Pullet) 35 g

Traditional Sizes
Size        Mass
Size 0 Greater than 75g
Size 1 70 g - 75 g
Size 2 65 g - 70 g
Size 3 60 g - 65 g
Size 4 55 g - 60 g
Size 5 50 g - 55 g
Size 6 45 g - 50 g
Size 7 less than 45 g