By Ku · Updated April 2026 · 10 min read
For years, the answer was simple: Walmart is the cheapest. End of story. No need to think twice.
But here's the thing — that assumption is outdated.
A spring 2026 survey by Consumer Reports compared grocery basket prices across six major U.S. cities, and the result genuinely surprised a lot of people. Costco came in 21.4% cheaper on average than Walmart. And a separate shopper comparison of 32 everyday items found Costco running nearly 26% cheaper once you factor in unit pricing.
That's not a small gap. That's real money.
But before you run out and grab a Costco membership, there's something important to understand: Costco doesn't win everything. And if you're not shopping the right way, you can actually end up spending more at Costco than at Walmart.
What the 2026 Research Actually Found
Consumer Reports tracked a standard grocery basket across Boston, Chicago, Dallas, Denver, L.A., and Virginia Beach — and Costco won in every single city. Here's how the major stores stacked up against Walmart:
| Store | Price vs. Walmart | Membership Required? |
|---|---|---|
| Costco | 21.4% cheaper | Yes ($65/year) |
| BJ's Wholesale | ~21% cheaper | Yes |
| Lidl | ~8.5% cheaper | No |
| Aldi | ~8.3% cheaper | No |
| WinCo | ~3.3% cheaper | No |
Whole Foods, for the record, came in nearly 40% more expensive than Walmart. So if you've been avoiding Whole Foods for your budget's sake — you're making the right call.
Why Costco Is Cheaper (When It Is)
Costco's pricing model is genuinely different from traditional retail. Instead of selling hundreds of brands and making a small margin on each, Costco sells a limited selection in large quantities and keeps its markup at around 14–15%. Most retailers mark up products anywhere from 25% to 100%.
And here's the real kicker: Costco doesn't need to profit on the groceries. They make most of their money from membership fees. That's what allows them to price items like toilet paper and peanut butter below what any traditional store can sustainably match.
A Quick Look at the Numbers
Here's a snapshot of where each store typically wins, based on current unit pricing:
| Item | Walmart Unit Price | Costco Unit Price | Winner |
|---|---|---|---|
| Jif Peanut Butter | 18.5¢/oz | 14.6¢/oz | Costco |
| Toilet Paper (store brand) | 22¢/100 sheets | 21¢/100 sheets | Costco |
| Store-Brand Laundry Detergent | 11¢/load | 15¢/load | Walmart |
| Store-Brand Olive Oil | 27¢/oz | 30¢/oz | Walmart |
| Eggs (per egg, bulk pack) | 37.3¢/egg | 24.9¢/egg | Costco (bulk) |
| Rotisserie Chicken | $6.98 | $4.99 | Costco |
See the pattern? Costco wins on items you use constantly and that store well. Walmart wins when you're buying smaller quantities — or when its store brand pricing is already aggressive enough to compete.
The "Bulk Illusion" Problem
Here's where a lot of shoppers get tripped up. They see a giant tub of something at Costco, do the math, and think they're saving money. But if you throw away 30% of it because it expired or went stale — your effective unit price just jumped by 42%. At that point, Walmart would've been the smarter buy all along.
The Dollar Habits rule on this: bulk buying only saves money if your household has a predictable, consistent use for that item. Toilet paper? Buy it at Costco all day. Fresh spinach for one person? Walmart every time.
What's in This Series
Instead of cramming everything into one giant article, I broke this comparison into focused guides. Each one tackles a specific part of the puzzle:
- Are Eggs Cheaper at Costco or Walmart? — The answer depends more on your household than you'd think
- The Toilet Paper Math: Kirkland vs. Great Value — Where the real per-sheet savings hide
- 10 Things That Are Almost Always Cheaper at Costco — The items that make the membership worth it
- 5 Things That Are Cheaper at Walmart — The categories where Costco doesn't win
- 5 Items You Should Never Buy at Costco — The bulk traps that cost you more
- Is a $65 Costco Membership Actually Worth It? — The real ROI math, category by category
The Bottom Line
Costco is the math winner in 2026. The data is pretty clear on that.
But Walmart is still the right call in plenty of real-life situations — smaller households, fresh food, items with short shelf lives, and anything where you can't commit to buying in bulk.
The smartest shoppers don't pick one store and stick with it religiously. They use both intentionally.
Once you understand where each store wins, grocery shopping stops feeling random — and starts feeling like a system that actually works for your budget.
— Ku
