In the battle for America's grocery shoppers, budget-conscious consumers are constantly weighing bulk savings against discount simplicity. A 2026 study from YouGov BrandIndex examined value-for-money perceptions between warehouse giant Costco and discount supermarket chain Aldi, revealing a shifting competitive landscape — especially among younger shoppers.
Across all U.S. adults, Costco maintains a modest overall lead in net value perception with a score of 38, closely followed by Aldi at 35. However, consumer attitudes vary significantly when broken down across generational lines:
- Gen Z — Costco holds a notable advantage with an average year-to-date net value score of 44 compared to Aldi's 32 (a 12-point gap).
- Millennials — Costco leads 43 to 34 (a 9-point gap).
- Gen X — Aldi pulls ahead slightly with a 35 to 33 score over Costco.
- Baby boomers — The two retailers are deadlocked in a tie at 37.
While Costco's overall dominance among younger demographics looks strong on paper, a deeper analysis throughout 2026 shows that its advantage over Gen Z has become far more volatile. Gen Z shoppers represent a vital growth segment for both retailers, accounting for 18% of Costco's active customer base and 13% of Aldi's.
Costco opened the year on Jan. 1 with a commanding 19-point lead among Gen Z (scoring 46 versus Aldi's 27). That lead fluctuated as Aldi's score climbed during late winter, but Costco surged again into the early summer, peaking at 51 on June 7 while Aldi stood at 33.
By late summer, however, the narrative shifted. Between mid-June and late August, Costco experienced a steady decline in perceived value among Gen Z, dropping from 48 at the end of June down to 38 by Aug. 31. Over the same stretch, Aldi remained relatively stable around 33, allowing the discount grocer to dramatically close the gap.
“Costco leads Aldi on value for money among U.S. adults, but its lead among Gen Z adults narrowed from 19 points at the start of January to 5 by the end of August,” says Kenton Barello, senior vice president at YouGov. “Over the summer, that narrowing was driven largely by declining perceptions of Costco's value. For grocery retailers, the findings show how quickly a lead on perceived value can shrink.”
As grocery stores head into the high-volume autumn and holiday shopping seasons, the data underscores a key takeaway for retail strategists: Brand perception among younger generations is highly dynamic. While Costco still holds the overall value crown, Aldi's momentum and Costco's summer decline suggest that Gen Z's loyalty remains up for grabs.
