Wondering how local your dairy products are? There's a printed code that shows where your milk and cheese were produced and packaged—here’s how to read it.

There's more to expiration dates and "best by" codes than you may think—for example, the expiration information on egg cartons can actually tell you when and where your eggs were packed. The key is locating a range of three consecutive numbers located near the "best by" date on your egg carton, which is a code based on the Gregorian calendar and tells you the exact day when your eggs were packed and shipped to supermarkets.

The USDA has another code that conveys where the eggs came from—and that labeling system actually applies to dairy products, too.

If you shop at a national grocery chain, there's a good chance that your milk and cheese traveled from far away to reach you, but you won't need to convert numbers or consult a Gregorian calendar to know where exactly your dairy comes from. Turns out, there's actually a website that converts the packing information for you.

It's called "Where Is My Milk From?" and it's free to use—you'll have to locate the “secret” packing code on the packaging, which is almost always located near the expiration date. It'll start with two numbers followed by a hyphen and another chain of numbers: 01-343, for example. The Food and Drug Administration has issued these codes to each and every state, so "01" would represent milk bottled in Alabama: you can learn more about how these items are labeled right here.

Credit: Photo: Zee Krstic

More tips and hacks for shopping smartly:

I tried decoding the dairy in my fridge using this hack, and I discovered that a bottle of milk purchased at Winn-Dixie was bottled at Dairy Farmers Of America, a group of producers based in Knoxville, Tennessee, which isn't too far away from my apartment in Birmingham, Alabama.

After you use the dairy decoding website once, you'll find yourself looking for the location code on your products all the time—after all, some supermarkets tout their commitment of sourcing local food, so understanding how to read this label could help you avoid buying dairy that’s traveled too far for your taste.