Costco's milk has a secret that most shoppers don't know

There are a million reasons to love Costco, starting with the budget-friendly prices. Other reasons Costco has so many die-hard fans are the company's generous returns policy, its commitment to quality, and the always-friendly team of employees.

Then there is the treasure-hunting aspect of a visit to Costco.

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Anyone who can leave the store without at least one unplanned purchase has a superpower. Whether it's a dog bed, a new set of towels, or that bestselling book you didn't know you needed, impulse purchases are hard to avoid.

While Costco carries fewer items than a traditional grocery store — you'll typically find around 4,000 SKUs vs. 30,000 at other grocers — you'll always find the staples you need for your refrigerator and pantry.

And let's be real. Most people shop at Costco for everyday needs like bread, cereal, meat, eggs, and milk.

Costco milk seems to last beyond its expiration date.

Image source: Shutterstock

Costco's staple foods are a big draw

Dairy items are probably on most people's Costco lists. Earlier this year, Costco faced egg shortages and was forced to limit the number of eggs customers could buy, but I've never seen the milk shelves empty.

The huge Costco cooler is stuffed with so many milk options that it can be overwhelming.

Whole vs. skim, check. Organic vs. conventional, yep. Lactose-free? Half-n-half or whipped cream? They've got it all. And out on the shelves, you'll find almond, soy, and coconut milk substitutes that don't need refrigeration.

But one thing you might not know about Costco's cow's milk products is that they often last well past their “expiration” dates.

Are Costco expiration dates real?

I recently discovered that expiration dates might be a suggestion instead of a rule when I poured some heavy cream into my coffee and then noticed it was a full week past its expiration date.

The cream didn't curdle, a telltale sign that the product had gone bad, so I shrugged and drank my delicious creamy brew. I continued to use the cream for another few days, and it was all gone before it actually went bad — by that point, it was a full 10 days past the expiration date.

Then I started to notice that the whole milk I buy from Costco also seemed to be just fine well past the date stamped on the side of the jug.

That got me curious, so I looked into it.

On one of the many Costco subreddits, dozens of people shared their comments about Costco milk, and many of them had the same experience.

In some cases, the milk lasted for two months (!) beyond its date.

There are a few theories as to why.

How valid are expiration dates anyway?

All companies are subject to the USDA rules around expiration dates, including Costco. But Costco doesn't just meet the USDA's minimum standard. It goes beyond and requires its vendors to do extra testing. According to Costco's 2023 Food Safety & Quality Audit Expectations, milk suppliers undergo surprise inspections at least once a year and if they don't pass, their products don't make it to stores.

Costco's Kirkland brand milk is also “ultra pasteurized,” defined by the USDA as a product that has “been thermally processed at or above 280°F for at least 2 seconds, either before or after packaging, so as to produce a product which has an extended shelf life under refrigerated conditions.”

Why Costco milk lasts so long

Those few seconds could extend the shelf life. Plus, not all dairy products experience the same delivery processes.

As one commenter said, “Costco is buying an 18-wheeler at a time. The 18-wheeler leaves the dairy (wherever it is, near or far), and goes straight to a store. Your local grocer, even a big boy like Kroger or Albertson's, doesn't sell through an 18-wheeler. The truck goes from the dairy to a Kroger warehouse, then sits there for a few days as they send a pallet at a time to individual stores. That whole process adds days or a week to shipping times,” which certainly could affect freshness.

There are some products I'd never use past their sell-by or expiration date — like meat or chicken. But milk? Cheese? Yogurt? Unless it smells rank or curdles in my coffee, I'm okay with using it.

If you're throwing out milk just because of the date on the label, you might be wasting perfectly good food. Costco’s ultra-pasteurized milk and direct shipping help it last longer — which could save you money and cut down on food waste.