There is a formula for figuring out which size of eggs is a better buy, in the sense of more volume of egg for your money. I didn’t understand the formulas in the articles I read about it, so I had work it out for myself from scratch. (That was an hour of my life I’ll never get back.)
The first thing to know is that egg sizes are by weight. The difference in the weight from one size to the next is 3 ounces. Small is 18 ounces up to jumbo at 30 ounces per dozen. A carton of a dozen large eggs weighs 3 ounces more than carton of a dozen medium eggs. This means that the increase in the amount you pay from one size to the next larger size is the amount you are paying for 3 more ounces.
For this example let’s say that the prices at the store this week are as shown below (I made them up). Let’s also say they are all ordinary white eggs, so the only difference is size.
A dozen jumbo eggs weigh 30 ounces and cost $2.49 or 8.3 cents an ounce and each three ounces costs 0.25 cents.
A dozen extra large weigh 27 ounces and cost $2.09, 7.7 cents an ounce and each three ounces costs 0.23 cents.
A dozen large eggs weigh 24 ounces and cost $1.79, or 7.5 cents an ounce and so 0.22 cents for three ounces.
A dozen medium eggs weigh 21 ounces and cost $1.59, or 7.6 cents an ounce, 0.23 cents for three ounces.
A dozen small eggs weighs 18 ounces and cost $1.49, 8.3 cents per ounce and 0.25 cents for three ounces.
In this example the Jumbo costs 0.40 cents more than the XL, so you’re paying 0.40 cents more for the three ounce difference.
Okay, so let’s say I went into the store thinking I’d buy a dozen medium eggs. But then I ask myself, would large eggs be a better value? In this example medium eggs cost 23 cents for each 3 ounces. Large eggs cost 22 cents per 3 ounces, so they’re already a better buy by weight. The extra 3 ounces costs just 20 cents (the difference between $1.59 for the medium and $1.79 for the large is 20 cents), so that additional 3 ounces is a bargain.
Knowing that a dozen large eggs weighs 24 ounces lets you figure out the per-pound cost. Divide the price by 24 to get the per ounce price and then multiply by 16 ounces in a pound. In this example the dozen costs $1.79. $1.79 divided by 24 ounces per dozen is 7.5 cents per ounce. 7.5 cents times 16 ounces in a pound tells you these large eggs cost $1.20 a pound.
I must admit I’m still confused about these egg formulas even after working it out for myself. What I do know is that eggs are a relatively inexpensive source of good quality protein. They’re versatile, useful in many types of dishes.