BJ's and Costco can both save you money—but if you want to shop online, this one's the better deal

Wholesale clubs can be a great way to save some serious cash, especially if you're shopping for an entire household. But which offers the best deals without your having to leave the house? We decided to put BJ's and Costco to the test.

To determine which store generally has the lowest prices for bulk items, CNBC Make It compared BJ's and Costco prices listed online that are available to members through home delivery options in the New York City area. We evaluated both national brands and each company's store brand when those were available.

After crunching the numbers on 26 grocery items — including fresh produce, baking ingredients, meat, and household items such as trash bags and laundry detergent — BJ's came out ahead in 18 categories where both retailers sold a similar product.

Here's how each store stacks up.

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When frugal shopping expert Lauren Greutman did a similar comparison between BJ's, Costco and Sam's Club on 40 products, she also found that BJ's prices were generally the cheapest.

While we verified the prices listed above with BJ's, Costco declined to verify its prices since, a spokeswoman said, they can change on a daily basis.

BJ's and Costco are, in some ways, parallel to Walmart and Target, Greutman says.

"Costco has a bit of a cult following because it's a little more high-class, it's nicer inside and they have a lot more free samples and things like that," Greutman says. Some shoppers find those perks enticing: "It's a little bit cleaner, a little happier and makes you feel good, like Target makes you feel over Walmart."

But BJ's more stripped-down approach generally yields more affordable options across the board, she says. In CNBC Make It's comparison, there were several items that the retailer sold at roughly half the cost of Costco: Gala apples, Wellsley shredded mozzarella cheese and Berkley Jensen ultra-soft toilet paper.

You could save even more if you use coupons. "Wholesale clubs don't traditionally accept manufacturer coupons, but BJ's is the exception, which provides you a great way to save money," Krazy Coupon Lady co-founder Joanie Demer tells CNBC Make It. BJ's takes both manufacturer and in-store coupons.

Price, of course, is not the only relevant factor: Quality matters as well. That's another reason many shoppers are loyal to Costco.

In Consumer Reports' 2018 Supermarkets survey of over 75,000 people, the publication rates Costco slightly higher than BJ's in general when comparing the stores on a variety of factors including cleanliness, competitiveness of prices, quality and the selection of healthy options.

Shoppers particularly called out the quality of Costco's meat and poultry options, as well as the store's Kirkland brand. Costco's Kirkland Signature bacon took top marks from Consumer Reports in their tests.

"The Kirkland brand is first-rate," says John Karolefski, grocery store analyst and editor of Grocery Stories. "The quality is very good."

Getting in the door at Costco and BJ's may cost more than your local grocery store, yet often the trip is worth it. "That membership fee allows them to reduce markups lower than any other stores, making Costco and BJ's and Sam's Club prices often 10% lower than you'll see anywhere else," Demer says.

For our comparison, we evaluated items available for home delivery, either through same-day delivery or through shipping from the stores' warehouses. However, Costco says, items may be cheaper when shopping in-store. Indeed, Consumer Reports found that grocery prices for same-day delivery were 31% higher at Costco than the ones in the store.

So if you can get to the store in person, Costco may be a good bet. It may also be easier to find: The wholesale club has locations in 44 states, as well as international outposts, as opposed to BJ's, which has over 200 stores spread across just 16 states.

You may also find prices at BJ's to be better in-store, especially when compared to same-day delivery costs. But if you do find a better deal through their website, BJ's policy notes they will match the difference in the form of a gift card, according to the Krazy Coupon Lady site.

If you're pressed for time, both do offer delivery, though.

To qualify for free shipping on your two-day delivery from Costco, you need to spend a minimum of $75. For same-day delivery through Instacart, prices include a service and delivery fee. With Instacart, local shoppers will buy the items you request from Costco, as well as other participating stores, and deliver to your doorstep. The minimum order for that service is $35, according to Costco.

BJ's also offers same-day delivery through Instacart and there's no fee on orders over $35, although the retailer says service fees may still apply. To use same-day delivery, you must spend at least $10. BJ's also offers free 3-5 day shipping on a number of non-perishable items purchased online.

To shop for most items at BJ's and Costco, you typically need your own paid annual membership. A Costco membership starts at $60 a year for the basic version. There are ways to avoid paying, but if you're a regular shopper it often makes sense.

A BJ's in-store membership starts at $55 a year. The retailer offers a $10 online access membership if you only want to shop through their website. BJ's also routinely offers discounted memberships to new customers.

No matter where you shop, make sure you're thinking ahead when it comes to purchasing products in larger quantities. You need to be able to eat any perishable food before it goes bad, for example. If you live by yourself, springing for Costco's 1-pound container of fresh spinach may not be cost-effective, even though it is a steal at $5.49.

"The thing you have to do is to remember to shop strategically and, wherever possible, stick to a list and a budget," Demer says.

Don't miss:

• We compared grocery prices at Costco and Boxed— here's which store will save you more money
• 9 foods and grocery items you should always buy at Costco
• 4 ways to shop at Costco without a membership that could save you money

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