Using Walmart as the benchmark, Consumer Reports found that only six grocery retailers nationwide consistently offer lower prices than the Arkansas-based superstore.
Costco claimed the top spot. While the warehouse giant charges a $65 annual membership fee, its deep discounts - especially on bulk purchases - more than offset the upfront cost for many shoppers.
BJ's Wholesale Club, which operates on a similar model with a $60 membership, followed closely behind in second place.
Next were German discount chains Lidl and Aldi. Both have long been popular across Europe, earning loyal followings for their no-frills stores and consistently low prices.
Lidl expanded into the US in 2017 and now operates nearly 200 stores. Aldi entered the market in 1976 and has grown to more than 2,600 locations nationwide, with further expansion planned.
WinCo Foods, an Idaho-based, employee-owned grocery chain known for its warehouse-style layout and rock-bottom pricing, also edged out Walmart.