Is it cheaper to buy groceries at Costco or Walmart?

Yes, on a per-unit basis, it is significantly cheaper to buy groceries at Costco than at Walmart. Recent comparisons show that Costco's grocery prices are, on average, about 21% lower than Walmart's.

However, deciding which store is actually cheaper for your wallet depends on how you shop:

• Unit Price vs. Total Cost: Costco wins on the price per ounce or pound. But because Costco only sells items in bulk, your checkout total will likely be much higher. If you end up throwing away spoiled food because you couldn't eat a bulk package fast enough, you lose those savings.
• Membership Fees: Costco requires an annual membership (starting at $60), which you must factor into your overall grocery budget. Walmart is free to shop at.
• Selection: Walmart allows you to buy exactly what you need—whether that's a single onion or a half-gallon of milk—making it better for small households or quick top-up trips.

If you have a large family, ample freezer space, and can eat what you buy before it goes bad, Costco is the clear winner for grocery savings. If you are shopping for one or two people and prefer not to pay a membership fee, Walmart is usually the more practical choice.