How Long Costco's Most Popular Products Are Good For After Opening Them

Costco is a treasure trove for shoppers looking to save money by stocking up on bulk items, from huge hunks of gourmet cheeses to massive jars of olive oil, tubs of Greek yogurt, and large packages of fresh bakery items. The allure of buying in bulk is undeniable, namely the savings, convenience, and joy of not having to shop every week. But lurking behind the satisfaction of stocking up lies a question that often goes unanswered until it's too late: How long are Costco's most popular products good for once you open them?

With sustainability and food safety at the front of many consumers' minds, it's more important than ever to know the lifespan of our bulk purchases to make sure that we actually are saving money and not literally throwing it away. Here, we'll go over the shelf life of some of Costco's fan favorites to help you make the most of your latest warehouse shopping haul. Whether you're a seasoned Costco shopper or a newcomer to wholesale shopping, we're here to ensure that you enjoy every last bit of your bulk buys without compromise.

Kirkland Signature Parmigiano Reggiano

There's nothing like topping pasta or pizza with freshly grated parmesan cheese. Costco makes it easy to access some of the best cheese with its Kirkland Signature Parmigiano Reggiano Straveccho. Fans of high-quality cheeses love the two-pound block from the wholesale club thanks to the fact that it is imported from Italy and is a certified Protected Destination of Origin (DPO) product. In addition, Costco's Parmigiana Reggiano is aged for a whopping 36 months. But is it safe to buy this cheese if you're not planning on hosting a giant group for Italian-themed dinner night?

You should be just fine, assuming you take care of the cheese properly. Vacuum-packed Parmigiano Reggiano can be stored in your refrigerator for several months. Once opened, you can safely keep the cheese in your fridge for about one month, given that the Costco Parmigiana Reggiano has been aged for longer than 24 months. If mold appears on one part of the cheese, you should be okay to simply cut off the affected portion with a knife and use the unblemished cheese as you would normally. You might consider freezing your cheese, but know that this can affect the texture of the defrosted product and you may want to shred your parmesan and double (or even triple) seal it before trying this trick on a portion.

Costco Bakery Sheet Cake

Everybody loves to have some cake with a celebration, be it a graduation, a birthday, an anniversary, or any other occasion. In addition, as adults, we reserve the right to buy ourselves a cake whenever we want even if there's nothing particularly exciting happening. So, it's great to hear that Costco's in-house bakery is known for selling delicious and affordable sheet cakes for any occasion, be it special or mundane. That said, Costco's take on sheet cake is on par size-wise with other products sold at the wholesale club — in other words, it can be huge. How well, if at all, does Costco's sheet cake last over time?

Generally, most cakes are good at room temperature for three to four days, so long as they're covered. However, even with thorough wrapping, the cake will start to dry out significantly and lose that moist texture we all know and love. If you want to extend the life of the cake you can put it in the fridge with plastic wrap against the cut edges to keep in moisture as best as you can. You may also want to consider portioning the cake into slices and freezing them. One Reddit user suggests storing Costco sheet cake slices by taking a folded piece of parchment paper, putting it around the knife, and sliding it into the cut you made in the cake before freezing. This way, it will be easier to remove single pieces to thaw for individual servings.

Kirkland Signature Organic Pure Maple Syrup

Delicious, organic maple syrup is the perfect addition to any breakfast, whether you're topping pancakes and waffles or sweetening your morning oatmeal or yogurt. Buying the freshest, highest-quality maple syrup is expensive, however. So, it's no wonder why people turn to Costco for its Kirkland Signature Organic Pure Maple Syrup. The 33.8-ounce container is filled with 100% pure Grade A amber maple syrup that's ready for all your breakfast dishes.

As for how long the maple syrup is good for once you open it, the consensus is that 100% pure maple syrup should last you about a year – assuming you've stored it in the fridge after opening the bottle. If you haven't opened it, the bottle should be good almost indefinitely or certainly until the printed date on the package. For longer-term storage, maple syrup maintains its flavor the best when it's kept in the freezer. This is good news for any maple syrup fans who don't have a large family or don't use maple syrup daily.

Kirkland Signature Organic Creamy Peanut Butter

A must-have product for nearly all household kitchens is creamy peanut butter. This protein-packed spread is as versatile as it is great tasting, making everything from sandwiches to yogurt to baked goods more delicious. So, with a Costco membership in hand, it's no wonder everyone from singles to families with kids likes to stock up on Kirkland Signature Organic Creamy Peanut Butter. The two-pack of 28-ounce containers is filled with USDA organic creamy peanut butter that is made with dry roasted peanuts sprinkled with sea salt.

With products of this size, it's not unusual to be concerned if your household can really use all of the peanut butter up before it goes bad. As it turns out, this Costco peanut butter lasts for about a month once opened. This is significantly less than the shelf lives of other kinds of processed peanut butter that have been made with preservatives. However, it's not all bad news. The fact that the pack contains two separate jars means that the shelf life is extended so long as you just open one jar at a time. Because this peanut butter is free of preservatives, it should be kept in the fridge much like many other organic brands of this sandwich stuffer.

Kirkland Signature Bacon

To many, bacon is a quintessential ingredient for everything from breakfast to lunch to dinner. It seems as if bacon lovers can never quite get enough of the salty, savory, flavor bomb. If you consider yourself to be in that crowd, then Costco is a great place to get bacon. That's because the wholesale club offers a four-pack of one-pound packages of hickory smoked bacon. As with most of Costco's products, buying bacon in bulk can be both a time and money saver, so long as you know how quickly you should enjoy the stuff.

However, four pounds of bacon is a lot. That's all the more daunting when you learn that even unopened packages will generally last about two weeks in your refrigerator. Of course, if you want to extend the life of the product you can freeze the unopened packages and thaw them out one at a time, which should be fine for a relatively high-fat product such as bacon. That said, even frozen bacon tends to lose its quality after a month or so. Once opened, raw bacon typically lasts around a week so long as it's refrigerated. If the bacon is cooked, you can only expect to get four to five days out of it before you should toss the leftovers.

Kirkland Signature Basil Pesto

There is nothing that says spring and summer quite like basil pesto, a staple in Italian cooking that's traditionally made from freshly picked basil, nutty parmesan cheese, flavorful olive oil, and crunchy pine nuts. Basil pesto is delectable on pasta, pizza, sandwiches, or proteins like chicken. Making pesto yourself can be time-consuming and costly, which leads many to turn to pre-made varieties. For an economical and convenient option, Costco offers a 22-ounce jar of its Kirkland Signature Imported Basil Pesto that is ready to go.

If you're concerned as to whether you could use the entire jar before it goes bad, we've got some insight. For starters, pesto in general should last until the date on the package. Some users on Reddit claim to have used the Costco pesto for up to four months, but officially you should go by the date on the jar for safety's sake. You can also judge its state by the smell and appearance, knowing that it's always best to toss anything that seems off — it's better than getting sick, after all. If you would like to extend the life of the product, you can freeze the pesto in individual portions for an extension of up to six months.

Costco Rotisserie Chicken

Rotisserie chicken is a staple in many homes and delicious recipes thanks to its versatility, flavor, and convenience. Costco offers one of the best rotisserie chickens around, typically weighing in at around three pounds for around five to six dollars, depending on which Costco you're shopping at. Costco's rotisserie chicken serves as an excellent entree alongside some vegetables and potatoes. In addition, it can be stripped off the bone (and save those bones for soups and broths while you're at it). That meat can then be used for a variety of meals like sandwiches, tacos, casseroles, pasta dishes, and much more.

When meal prepping with a rotisserie chicken, how many days can you count on the meat to be safe to eat? Generally, rotisserie chicken can be stored in the refrigerator for up to four days. However, that shelf-life depends on you cooling and storing the chicken correctly beforehand. First, fully cooled chicken should be stored in a zip-top bag or another airtight container before it hits the fridge. Be sure that you never eat cooked chicken that has sat out for longer than two hours, as it could be a breeding ground for bacteria.

Kirkland Signature Milk Chocolate Almonds

Whether you're putting together a dessert-forward charcuterie tray for a get-together, enjoying a chocolatey snack while watching a movie, or looking for something sweet yet wholesome to add to a child's lunch box, Costco's Kirkland Signature Milk Chocolate Almonds are a great addition to any pantry. The three-pound jar features roasted almonds enrobed in mild milk chocolate. At around $17, depending on which Costco you shop at, the milk chocolate almonds are not only delicious but also represent a great deal. But how long will these candy-like snacks last once opened?

Generally speaking, chocolate-covered almonds should be stored in a cool, dry place. Do that, and they should last up from six months to a year depending on how well your particular storage location meets these criteria. As for Costco's Kirkland Signature Milk Chocolate Almonds, as with other products, be sure that you check the printed information on the jar to make sure that you're consuming the product before the best-by date.

Kirkland Signature Pure Vanilla

Vanilla extract is one of those ingredients that you simply must keep on hand if you enjoy cooking meals at home. It is an essential ingredient in delectable treats like cookies, cupcakes, and other baked goods. It can also be used to flavor a multitude of other dishes, from pancakes to coffee drinks, to yogurt parfaits and smoothies. As home cooks surely already know, however, quality vanilla can be a costly investment. Costco offers an affordable option that is still high quality with its 16-ounce bottle of pure vanilla extract made with imported vanilla beans for true depth of flavor.

Sixteen ounces of vanilla extract may sound like a lot — and it is — but luckily this is one ingredient that can be stored for quite a long time. In fact, because this vanilla extract is made with alcohol (35%, according to the bottle), it can be stored almost indefinitely. However, it's best used within a few years to take advantage of the deepest flavor the vanilla extract can provide. We also recommend checking the printed best-by date on the bottle to ensure you get the best possible flavor possible.

Kirkland Signature 100% Italian Extra Virgin Olive Oil

If there is one staple ingredient home cooks should consider purchasing in bulk, it is surely extra virgin olive oil. This powerhouse ingredient does it all in the kitchen. It is a key ingredient in many salad dressings and sauces, such as pesto and marinara, while it's also often used as a cooking oil to give food flavor and crunch. Olive oil can also be used in baking, giving a unique flavor and texture to cakes and breads. Many Costco shoppers swear by the wholesale club's Kirkland Signature Extra Virgin Italian Olive Oil, which comes in a two-liter container.

We admit that two liters represents a lot of olive oil, so it is best to know how long the product will last before you purchase it. You simply can't risk wasting a lot of this kitchen must-have ingredient. Generally, extra virgin olive oil has a 12 to 18-month shelf-life after it has been opened. It is best to store it in a cool, dry place to get the most out of this time. Also, be sure that the oil is stored in a dark container to avoid light damaging the product.

Kirkland Signature Croissants

When strolling the aisles of Costco, nothing is more tempting than the freshly baked goods at the wholesale club's bakery. From cakes to cookies, to bagels and fresh bread, the Costco bakery has it all. One of the store's best sellers is its 12-count package of scratch-made croissants. The buttery, flakey baked good is perfect for toasting for your morning breakfast or dipping in chocolate for a decadent dessert. However, if you live in a smaller household, a dozen croissants can be hard to get through before they go bad.

To make sure you are enjoying your Costco bakery croissants to the fullest before they get dried out, hard, crumbly, or moldy, it's best to eat them within four days of the sell-by date. This is according to a Redditor who claims to work in the Costco bakery, "Bakery products only have sell-by dates, not best-by. Most products are good for four or more days after the sell by date," they wrote. If your croissants are past their prime but free of visible mold, the same purported employee said not all hope is lost: "Pop them in the oven or an air fryer for a few minutes and they'll taste close to fresh."

Kirkland Signature Organic Large Brown Eggs

Eggs are one of the most versatile ingredients you could have in the kitchen. They are simply a must-have for households and families of all sizes, making hearty breakfasts, light lunches, and protein-packed snacks. And did we mention deviled eggs? There are many ways to enjoy eggs, and with prices of this nutritional power ingredient still fairly high (though they're at least cheaper than they once were), consumers are understandably looking for ways to save money on them.

Costco's Kirkland Signature Organic Large, Cage Free Brown Eggs are a popular staple for shoppers of the wholesale club not only because of the high quality but also because of the great price. Yet, for some households, two dozen eggs may seem to be too many to justify purchasing this perishable item in bulk. However, according to the USDA, eggs can be refrigerated for three to five weeks from the day you bring them home. The USDA also states that it is important to note that the sell-by date is not the same as a product's best-by or consume-by date. As long as eggs are stored at 40°F or slightly below, they should be good for three to five weeks. Once boiled, eggs are good for one week if they are stored in the refrigerator.

Kirkland Signature Greek Yogurt

Whether you are a health nut or just enjoy a satisfying meal or snack without the hassle of cooking, Greek yogurt is a great way to get some protein. Greek yogurt can be eaten alone with granola and fruit, used in smoothies and shakes, or mixed into savory dishes to add creaminess and tang.

For yogurt fans, Costco is a great place to purchase a large amount for a smaller price tag compared to what's on offer at your local grocery store. Costco's Kirkland Signature Organic Greek Nonfat Yogurt, Plain is available in a three-pound tub. Sold for around $8, depending on the Costco location you happen to be shopping at, this is a great deal. 

But can your family consume all of the yogurt before it goes bad? Generally, an opened container of Greek yogurt lasts around two weeks in the fridge or two months in the freezer (though not all yogurts freeze well, so check the ingredients list to see if it contains pectin or gelatin that helps yogurt fare better in the freezer). If you notice liquid on top of the yogurt, don't stres. A small amount of liquid on top of Greek yogurt is mostly water with some nutrients that have separated. Simply stir it into the yogurt before eating. However, if there is an abundant amount of liquid, mold growing in your tub, or it has been more than two weeks since you opened the container, it's best to toss it.