At first glance, Trader Joe's and Costco couldn't be more different. TJ's stores are fun, quirky, and smaller than most supermarkets. Costco is the complete opposite — utilitarian and truly cavernous in size. Yet they actually have a lot in common. For example, both are known for carrying a wide array of organic foods, and both are known for offering some of the lowest prices in the industry.

Of course, shopping at Costco means buying, say, four pounds of quinoa instead of one, which requires a bigger up-front investment both in terms of money and pantry space. Which is a better deal? Can Costco's bulk prices beat Trader Joe's ounce for ounce?

We set out to answer this burning bargain-shopping question by comparing the prices of common groceries at both stores. In some cases, the difference is negligible, and you can save your precious kitchen real estate for other things. But there are definitely more than a few items that make buying in bulk worthwhile.

Breakfast Items

1. Greek Yogurt

Consumer Reports gave high marks to Kirkland Signature Greek yogurt, placing it at number 5 versus Trader Joe's at number 13.

• WINNER! Costco's Kirkland Plain Nonfat: $5.89 for 48 ounces ($0.12 per ounce)
• Trader Joe's Plain Nonfat: $2.75 for 16 ounces ($0.17 per ounce)

2. Frozen berries

Berries soak up pesticides like a sponge, which is why it's best to buy organic whenever possible. Both Costco and TJ's stock bags of frozen organic mixed berries perfect for smoothies, oatmeal, and baked goods.

• WINNER! Costco's Kirkland Organic Three-Berry Blend: $9.59 for four pounds ($0.15 per ounce)
• Trader Joe's Organic Mixed Frozen Berries: $2.99 for 12 ounces ($0.25 per ounce)

3. Bananas

Trader Joe's prides itself on the low price of its bananas, which reportedly hasn't changed in years. But even in this category Costco has them beat.

• WINNER! Costco: $1.39 for 3 pounds, or about nine bananas ($0.15 each)
• Trader Joe's: $0.19 each banana

4. Milk

If you have room for two gallon-sized jugs of milk, and can go through it fast enough, Costco is the way to go, saving you nearly 50 cents a gallon.

• WINNER! Costco: $4.59 for two gallons ($2.30 per gallon)
• Trader Joe's: $2.79 per gallon

5. Eggs

Labeling on eggs is tricky and confusing enough to warrant an article (or seven) of its own. Still, organic is a good thing and certified humane, cage-free, and free-range are all better than conventional factory farming. Both stores offer great deals on eggs with these feel-good labels.

• WINNER! Costco organic, certified humane and cage-free large eggs: $6.39 for two dozen ($0.27 per egg)
• Trader Joe's organic, free-range large eggs: $3.99 for a dozen ($0.33 per egg)

6. Bacon

Consumer Reports gives Costco's private label bacon high marks for flavor. It's cured, though, whereas all of Trader Joe's bacon is "uncured" (read: cured with natural agents like celery powder rather than nitrates or nitrites).

• WINNER! Kirkland Signature Bacon: $16.99 for four pounds ($0.27 per ounce)
• TJ's Uncured Dry Rubbed Bacon: $5.49 for 12 ounces ($0.46 per oz)

Lunch and Snacks

7. Bread

If you have a household of sandwich eaters, it's easy to tear through two loaves of bread in a week, making Costco a great choice. Otherwise, tuck a loaf in the freezer, or pony up the three extra cents per ounce for the TJ's bread.

• WINNER! Costco Oroweat 100% Whole Wheat Sandwich Bread: $5.70 for two 32-ounces loaves ($0.09 per ounce)
• Trader Joe's Soft Whole Wheat Sandwich Bread: $2.99 for 24 ounces ($0.12 per ounce)

8. Deli Meat

Surprisingly, it won't save you any extra money (just one cent!) to buy your turkey lunch meat in bulk, although if you really love turkey sandwiches you won't have as much packaging to throw away.

• TIE! Kirkland Signature Oven Roasted Sliced Turkey Breast: $6.89 per pound ($0.43 per ounce)
• TIE! Trader Joe's Oven-Roasted Sliced Turkey Breast: $2.99 for seven ounces ($0.43 per ounce)

9. Albacore Tuna

Both stores carry private-label albacore tuna that's labeled dolphin-safe and caught by "monofilament leaders and circle hooks." They're almost the same price per can, but the cans are two ounces bigger at Costco.

• WINNER! Kirkland Signature Albacore Solid White Tuna in Water: $12.99 for eight, seven-ounce cans ($0.23 per ounce)
• Trader Joe's Albacore Solid White Tuna in Water: $1.69 for a five-ounce can ($0.34 per ounce)

10. Cheddar cheese

Both Costco and Trader Joe's have excellent cheese selections, with Costco dedicating a bit more shelf space to other premium cheese producers beyond their store brand. Their prices are lower too. The question is, how quickly can you go through five pounds of cheese?

• WINNER! Kirkland Signature Sharp Cheddar: $11.29 for five pounds ($0.14 per ounce)
• Trader Joe's Wisconsin Extra-Sharp Cheddar: $4.99 per pound ($0.31 per ounce)

11. Nuts

Both Costco and Trader Joe's are known for carrying high-quality nuts. They're cheaper in bulk at Costco, if you can use them up before they go rancid or have room in your freezer.

Pecan halves

• WINNER! Kirkland Signature Pecan Halves: $15.99 for two pounds ($0.50 per ounce)
• Trader Joe's: $4.99 for eight ounces ($0.62 per ounce)

Walnuts

• WINNER! Kirkland Signature: $12.99 for three pounds ($0.27 per ounce)
• Trader Joe's Walnut Halves and Pieces: $5.99 per pound ($0.37 per ounce)

Almonds

• WINNER! Kirkland Signature Raw Almonds: $12.99 for three pounds ($0.27 per ounce)
• Trader Joe's Raw Almonds: $5.99 per pound ($0.37 per ounce)

12. Granola Bars

The ubiquitous Kind Bars are a full 50 cents cheaper at Costco. The good news for TJ's shoppers: There's a private label version that's a good deal.

• WINNER! Costco Kind Bars Variety Pack: $19.99 for 20 bars ($1.00 each)
• Trader Joe's Kind Bars, flavors vary: $1.49 each
• WINNER! Trader Joe's Simply Nutty bars, flavors vary: $0.99 each

Dinner

13. Pasta Sauce

Turns out, buying marinara sauce in bulk isn't going to save you any money. Both stores sell their versatile sauces for the same price per ounce. Costco's jar is almost a full cup bigger, which is great if you make large batches of pasta. If not, though, you'll end up with annoying leftovers.

• TIE! Kirkland Signature Organic Marinara Sauce: $9.99 for three, 32-ounce jars ($0.10 per ounce)
• TIE! Trader Joe's Organic Marinara: $2.49 for 25 ounces ($0.10 per oz)

14. Ground beef

This is one case where buying in bulk is far cheaper, saving you about $2.50 per pound. You'll have to buy four pounds of Costco's organic ground beef, but it comes in one-pound packages so you can just toss them in the freezer.

• WINNER! Kirkland Signature Organic Ground Beef: $19.99 for four pounds ($5 per pound)
• Trader Joe's ground beef: $7.49 per pound

15. Dried Penne

You'll need to carve out some pantry space to bring home Costco's six-pack of three kinds of dried pastas imported from Italy. If you don't have the space, you're in luck: The Trader Joe's option is a few cents cheaper.

• Costco Garofalo Organic Pasta: $10 for six 17.6-ounce packages: ($0.09 per ounce)
• WINNER! Trader Joe's Penne Rigate: $0.99 for 16 ounces ($0.06 per ounce)

16. Chicken

Organic chickens not only eat organic feed — they're also raised without hormones or unnecessary antibiotics. Trader Joe's has the added advantage of being labeled free-range, but Costco will save you about $3 per bird. The caveat? You have to buy two.

• WINNER! Kirkland Signature Organic Whole Young Chicken: $1.99 per pound
• Trader Joe's Organic Free-Range Whole Chicken: $2.69 per pound

17. Salmon

Unlike the ground beef, there's no savings for buying your wild Alaskan salmon in bulk. Both stores offer it at the same price.

• TIE! Wild Alaskan Sockeye Salmon Fillets: $32.99 for three pounds ($0.69 per ounce)
• TIE! Trader Joe's Wild Alaskan Sockeye Salmon Fillets: $10.99 per pound ($0.69 per ounce)

18. Greens

Both stores offer bags with a blend of tender baby kale, spinach, and chard, but Costco's bigger bag is about half the price per ounce. And since greens cook way down, a big bag isn't a bad thing.

• WINNER! Costco Earthbound Farm Organic Power Greens: $4.99 for 1.5 pounds ($0.21 per ounce)
• Trader Joe's Organic Power Greens: $1.99 for five ounces ($0.40 per ounce)

Staples

19. Butter

Kerrygold — a rich, bright-yellow salted butter from Ireland — is a favorite among TJ's shoppers, where it's far cheaper than most other stores. But it turns out it's more than a dollar cheaper at Costco — you'll just have to buy eight times as much.

• WINNER! Costco: $10.99 for four pounds ($0.17 per ounce)
• Trader Joe's: $2.99 for eight ounces ($0.37 per ounce)

20. Olive Oil

Costco's Kirkland label olive oil consistently gets high marks for its flavor and quality, and is a go-to among food pros. Trader Joe's? Well, it depends. There are oils from Spain, Greece, Tunisia, and sometimes all three. Some are good, but it's not uncommon to pick up one that's past its prime. Luckily TJ's has a great return policy.

• WINNER! Kirkland Signature Organic Extra-Virgin Olive Oil from Italy: $15.99 for two liters ($0.24 per ounce)
• Trader Joe's Extra Virgin Italian Olive Oil: $5.49 for 16.9 ounces ($0.32 per ounce)

21. Quinoa

Packed with protein and essential amino acids, quinoa is a great alternative to rice. And when you think about all the side dishes in your future, a giant sack probably won't last that long.

• WINNER! Kirkland Signature Organic Quinoa: $9.99 for 4.5 pounds ($0.14 per ounce)
• Trader Joe's Organic White Quinoa: $3.99 for one pound ($0.25 per ounce)

When it comes down to it, which store do you prefer?