For some of your food shopping, membership warehouse clubs offer low-cost alternatives to supermarkets. We surveyed Costco and Sam’s Club. These warehouse stores carried few if any of the items in our market basket in the usual sizes, but when we looked for the same brands regardless of size, warehouse stores, which specialize in bulk sales, stocked a larger portion of our market basket items. Sam’s Club had 55 percent and Costco 45 percent.

The figure below indicates how much warehouse stores could save you. Since the warehouse stores stocked so few items in the sizes of our basic market basket, we looked for items of any size, so long as they were the same brands. We then used unit prices (for example, price per pound) to calculate the warehouse store’s prices for amounts specified in the market basket. After this adjustment, we compared the prices of items at the warehouse stores with prices for the same brands at several other stores. Bear in mind that this is not an “apples-to-apples” comparison; the sizes of the items priced at the warehouse stores were almost always larger than the sizes of the items priced at the other stores, so the warehouse stores enjoy an advantage in such a comparison.

The two warehouse clubs offer significant savings. Costco, for example, beat QFC’s prices by a whopping 31 percent. And compared to QFC, the savings were about 29 percent at Sam’s Club. On the other hand, while the warehouse clubs offered significant savings compared to even the lowest-priced stores, these savings perhaps aren’t enough to justify paying the clubs’ annual membership fees if you don’t use them often.

How Much You Can Save at Warehouse Stores

The graphs below show how much less expensive prices at the warehouse stores were compared to the listed supermarkets. For these comparisons, we shopped all stores to calculate the least expensive way to buy each item in our market basket, per unit, regardless of item size.

 
 

Since warehouse stores focus on selling items in large quantities but do not carry a wide range of products, you will probably need to supplement warehouse shopping with trips to the supermarket. The table below shows price comparison scores for shopping at two stores—purchasing available market-basket items at a warehouse, and then buying the remaining items at a supermarket. For instance, the price comparison score for buying all available market-basket products at Costco and then purchasing the remaining items at QFC is $80. Compare this to the price comparison score of $97 for buying all items at QFC (purchasing national brands of the cheapest size).

What If You Shop at Two Places: At a Supermarket and at a Warehouse Store
  Price comparison score if you shop only at supermarket Price comparison score if you buy available items at Costco and other items at supermarket Price comparison score if you buy available items at Sam's Club and other items at supermarket
Albertsons $96 $82 $79
Fred Meyer $91 $79 $77
QFC $97 $80 $78
Safeway $97 $83 $79
Walmart $77 $70 $71
WinCo $78 $73 $73