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 53 percent and Costco 42 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. Sam’s Club, for example, beat Cub’s prices by a whopping 26 percent. And compared to Cub, the savings were about 25 percent at Costco. On the other hand, while the warehouse clubs offered significant savings compared to Walmart and Target, these savings perhaps aren’t enough to justify paying the clubs’ annual membership fees if you don’t use them often.

In addition to low prices, Costco received high ratings for the quality of its fresh produce, meat, and overall quality. Sam’s Club, on the other hand, rated poorly for produce and for overall quality.

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 itemsize.