Kirkland Signature Protein Shake Nutrition (2026): 30g Protein, 160 Calories, ~$1.35 per Bottle at Costco

Costco’s Kirkland Signature Protein Shake is the cheapest ready-to-drink protein shake in America in 2026, and it is not close. Each 11.5 fl oz bottle delivers 30g of complete milk protein for 160 calories and 1g of total sugar — the same headline numbers as Premier Protein and effectively tied with Fairlife Nutrition Plan — but the Costco 18-pack lands at roughly $0.043–$0.048 per gram of protein, versus $0.078–$0.089 for Premier and Fairlife on Amazon. Below is the verified 2026 nutrition breakdown for both flavors, the honest sweetener story, who manufactures it (spoiler: Fairlife), how it compares against Premier and Fairlife Nutrition Plan bottle-for-bottle, and whether the Costco membership math actually works in your favor. For where this shake fits in the wider budget race, see our cheapest protein shakes 2026 guide. For the closest same-format alternatives you can buy without a membership, see Premier Protein shake nutrition and Fairlife Nutrition Plan nutrition.

Kirkland Signature Protein Shake Nutrition Facts (Per 11.5 fl oz Bottle)

The Kirkland Signature Protein Shake sells in Chocolate and Vanilla flavors, both in the same 11.5 fl oz (340 mL) shelf-stable bottle. Every bottle is one serving. The verified label numbers below match the current 2026 Costco listings and align with the same ultra-filtered-milk formulation Fairlife uses across its own product lines.

The Chocolate and Vanilla flavors are nearly identical on macros — the only real gap is 1g of extra carbohydrate in Chocolate (from the cocoa) and slightly more sodium. Both post 30g of protein, 1g of total sugar, and 0g of added sugar. That protein-to-calorie math works out to 18.75g of protein per 100 calories — tied exactly with Premier Protein and only a hair behind Fairlife Nutrition Plan (20.0g per 100 cal). For a shake this cheap, that is the strongest protein-per-calorie ratio you will find in the warehouse-club aisle.

Who Actually Makes It? Fairlife.

Kirkland Signature is Costco’s private label brand, but Costco does not manufacture its own protein shakes. The Kirkland Signature Protein Shake is manufactured by Fairlife LLC (a subsidiary of The Coca-Cola Company) at the same ultra-filtered-milk facilities that produce Fairlife’s own Core Power, Core Power Elite, and Nutrition Plan lines. Fairlife has confirmed the manufacturing relationship publicly, and the ingredient panels between the two brands are nearly identical — ultra-filtered lowfat milk base, the same sweetener stack, the same emulsifier and stabilizer choices, the same lactase enzyme treatment.

What that means in practice:

• The protein source is real ultra-filtered milk, not milk-protein-concentrate stirred into water. This is the same production process that lets Fairlife concentrate the milk’s native protein and strip most of the lactose. It is closer in taste and mouthfeel to real chocolate milk than to a powder-based shake reconstituted from water.
• The shake is effectively lactose-free. Lactase enzyme is added at production to break down the residual lactose, following the same protocol Fairlife uses across its own branded products. It is not explicitly labeled lactose-free the way Fairlife’s own products are, but the underlying formula is the same.
• The nutrition profile mirrors Premier Protein more closely than it mirrors Fairlife Nutrition Plan on calories, despite the shared manufacturing. Kirkland is 160 calories per bottle (like Premier), where Nutrition Plan is 150. That’s a formulation choice made for Costco, not a difference in the underlying milk.

The upshot: you are buying Fairlife-quality protein at Costco private-label pricing. That is the entire value proposition, and it is a genuinely good deal.

The Sweetener Story: Sucralose and Ace-K, Plus Monk Fruit and Stevia

The 1g total sugar / 0g added sugar label is not a coincidence — it is the result of a four-sweetener blend, the same one Fairlife uses across its own lineup:

• Sucralose and acesulfame potassium (Ace-K) — the two synthetic, non-nutritive sweeteners that do the heavy lifting on sweetness intensity. Both are FDA-approved and safe at typical intake levels; if you dislike the finish of either, this shake will taste sweetened to you.
• Monk fruit juice concentrate and stevia leaf extract — the two plant-derived sweeteners that Fairlife markets on the front of Nutrition Plan. They add sweetness and round out the flavor but are not typically the primary drivers of perceived sweetness in an ultra-filtered milk shake.

If you are avoiding all non-nutritive sweeteners, this shake does not qualify — the sucralose and Ace-K are on the ingredient panel and cannot be avoided. If you are avoiding only sucralose specifically, the same problem applies. This is one place where a Costco membership does not solve the sweetener question: every affordable RTD shake in the U.S. mainstream shelf uses at least one synthetic sweetener. For the closest sweetener-free alternative, Muscle Milk Genuine after its 2026 reformulation is the only major RTD shake that dropped sucralose and Ace-K — see our Muscle Milk nutrition guide.

The Real Value: Price Per Gram of Protein

The Kirkland Signature Protein Shake sells almost exclusively in Costco’s 18-count club case, at prices that vary slightly by warehouse but land consistently between $23 and $26. That works out to:

To put that in the context of every RTD shake on the U.S. market:

The Kirkland Signature Protein Shake is roughly 45% cheaper per gram of protein than Premier Protein on Amazon, and roughly 50% cheaper than Fairlife Nutrition Plan on the same Amazon multipacks. Over 100g of protein a week from shakes (three bottles), a Costco membership shaves $2.50–$3.00 off the weekly cost compared with the cheapest Amazon alternative. Over a year, that is roughly $130–$155 in savings on shakes alone — comfortably more than a Gold Star Costco membership ($65/year).

Kirkland Signature Protein Shake vs Premier Protein vs Fairlife Nutrition Plan

The three most-cross-shopped 30g RTD shakes on the U.S. market. All three deliver 30g of complete dairy protein in an 11.5 fl oz bottle with 0g added sugar. What separates them is calorie count, sweetener mix, and price.

The macro story is essentially a three-way tie on protein and sugar. Fairlife Nutrition Plan is 10 calories leaner (150 vs 160) and explicitly labeled lactose-free; Premier Protein has the fewest listed sweeteners; Kirkland ties Fairlife on protein source and ties Premier on calories, and beats both on price by a wide margin. If you have a Costco membership and are not lactose intolerant enough to need the explicit label, Kirkland is the pick. If you are strictly lactose-intolerant and want the label guarantee, Nutrition Plan is the safer choice. If you want the broadest added-vitamin coverage or shop primarily at grocery / Amazon, Premier remains a strong buy. For the direct Premier vs Fairlife breakdown, see our Premier Protein vs Core Power guide.

Where to Buy: Costco Warehouse or Costco.com Only

The Kirkland Signature Protein Shake is not sold on Amazon, and not sold at any other retailer. It is a Costco private label product and is available only through:

• In-warehouse at any U.S. Costco — typically stocked in the refrigerated dairy section or the beverage aisle, in the 18-count case. Costco requires a paid membership to shop in-warehouse.
• Costco.com — sold to Costco members with online delivery, sometimes at a slight price premium versus in-warehouse pickup.
• Third-party grocery delivery services (Instacart, DoorDash) — some markets list Costco inventory through these services, usually at a service-fee markup that can eat much of the savings.

Non-members cannot purchase these shakes at Costco.com or in-warehouse. If you do not currently have a Costco membership, run the math: a Gold Star membership is $65/year, and the Kirkland Signature Protein Shake pays for it after roughly 12–15 boxes over a year at the Premier Protein price differential (~$4.50–$5.00 saved per case). One case per month clears the break-even point in about 12 months on shakes alone — and Costco memberships pay dividends on plenty of other categories.

Best Uses for the Kirkland Signature Protein Shake

• Daily protein target on a budget. 30g of complete dairy protein for under $1.50 is the cheapest way to add a shake to your day short of buying whey powder. If you are hitting a protein target that requires 2–3 shakes a day (common for lifters over 180 lbs), the Costco price differential adds up to real money.
• Post-workout recovery. 30g of complete milk protein with a well-studied leucine content is well inside the range for post-training muscle protein synthesis. Ultra-filtered milk is a mix of whey and casein, which digests at moderate speed — slower than a pure whey isolate, faster than a straight casein shake.
• Meal replacement (in a pinch). 30g of protein and 160 calories make this a reasonable rushed breakfast or missed-lunch cover. Pair with fruit or oats to add fiber; alone it is not filling enough for a full meal.
• Weight loss / calorie deficit. High protein plus modest calories fits the classic weight-loss playbook. The Kirkland shake sits right beside Fairlife Nutrition Plan and Premier Protein in our best high-protein snacks for weight loss ranking; the Costco price advantage makes it the easiest to sustain long-term.
• Kids and teens who need extra protein. With a pediatrician’s guidance, a shelf-stable 30g shake can be a genuinely useful protein boost for a growing teen athlete. Note the artificial sweeteners — some parents prefer to avoid sucralose and Ace-K in kids’ diets. This is general information, not medical advice.

Who Should Skip It

• Anyone avoiding all non-nutritive sweeteners. Sucralose and Ace-K are on the ingredient panel and cannot be avoided in this product.
• Anyone with a milk allergy. Ultra-filtered milk is still milk; lactose-free is not dairy-free.
• Anyone with a soy allergy. The shake contains soy lecithin as an emulsifier. Fairlife Nutrition Plan is soy-free if you need a milk-based alternative.
• Non-Costco-members without an easy way to join. The shake is Costco-only. If a Costco is not accessible and you cannot justify a membership, Premier Protein on Amazon is the closest available alternative — see our Premier Protein shake nutrition guide.
• Anyone chasing maximum protein per bottle. Kirkland tops out at 30g. Fairlife Core Power Elite (42g / 14 fl oz) is the largest single-serve dose in the ultra-filtered-milk category — see our Fairlife Core Power nutrition breakdown.

Honest Caveats

• Not explicitly labeled lactose-free. The underlying formula is Fairlife’s ultra-filtered milk with lactase enzyme — effectively lactose-free — but Costco does not carry a “lactose-free” label on the Kirkland Signature bottle. If you have severe lactose intolerance and want the explicit label guarantee, buy Fairlife Nutrition Plan instead.
• Case size is a commitment. The 18-count case is the only stock-keeping unit Costco reliably carries. If you are not sure you will drink 18 shakes before the taste gets old, buy a Premier Protein 4-pack at a grocery store first.
• Flavor variety is thinner than Premier. Kirkland stocks Chocolate and Vanilla. Premier ships six core flavors plus rotating limited editions (Cookies & Cream, Caramel, Café Latte, Strawberries & Cream). If flavor rotation matters to you, Premier is the more entertaining case to buy.
• Price is warehouse-dependent. Costco pricing varies slightly by region, and periodic $3–$5-off in-warehouse promos push the price down further; occasional supply squeezes push it up. Always check the warehouse tag — the ranges above hold in most weeks but not all.
• Refrigeration. The Kirkland Signature Protein Shake is sold in Costco’s refrigerated cases — not shelf-stable Tetra Pak the way Premier Protein bottles are. Unopened bottles are fine at room temperature for a few hours in a gym bag or lunch box, but the whole case belongs in the fridge at home. Once opened, refrigerate and drink within 24 hours.

Frequently Asked Questions

How much protein is in a Kirkland Signature Protein Shake?

30g of complete dairy protein per 11.5 fl oz bottle, or 60% of the Daily Value. That’s the same protein count as Premier Protein and Fairlife Nutrition Plan and equal to about 4 oz of grilled chicken breast on a protein-only basis.

Who makes the Kirkland Signature Protein Shake?

Fairlife LLC, a subsidiary of The Coca-Cola Company. It is produced at the same ultra-filtered-milk facilities that make Fairlife’s own Core Power, Core Power Elite, and Nutrition Plan lines. The formulation is nearly identical to Fairlife Nutrition Plan on protein source and sweetener stack.

Is the Kirkland Signature Protein Shake lactose-free?

The underlying Fairlife formula uses ultra-filtered milk with lactase enzyme — the same process Fairlife uses to make its own products lactose-free. In practice the Kirkland shake is effectively lactose-free, though it is not always explicitly labeled as such on the Costco bottle. If you have severe lactose intolerance and need the explicit label guarantee, buy Fairlife Nutrition Plan instead.

Is Kirkland Signature Protein Shake sold on Amazon?

No. It is a Costco private label product and is sold only through Costco warehouses and Costco.com to members. Third-party services like Instacart sometimes list it at a service-fee markup, but Costco does not distribute it to Amazon, Walmart, Target, or any other retailer.

Does Kirkland Signature Protein Shake have artificial sweeteners?

Yes. The current ingredient panel lists sucralose and acesulfame potassium (Ace-K) as the primary sweeteners, plus monk fruit juice concentrate and stevia leaf extract. If you are avoiding all non-nutritive sweeteners, this shake is not the pick. The closest widely-available alternative without sucralose or Ace-K is Muscle Milk Genuine after its 2026 reformulation.

Is a Costco membership worth it just for the protein shakes?

For a daily-shake drinker, yes — the math clears the Gold Star $65/year membership fee after roughly 12–15 cases at the price differential versus Premier Protein on Amazon (~$4.50–$5.00 saved per case). One case per month for a year covers the membership on shakes alone, and Costco memberships pay dividends across many other product categories. For an occasional shake drinker, the membership math is harder — stick with Premier Protein multipacks on Amazon or at Walmart.

Are Kirkland Signature Protein Shakes healthy?

They are a convenient, high-protein, low-sugar drink — a clear upgrade over sugary coffee drinks, fast-food breakfasts, or skipping a meal. The trade-offs are that this is a processed, fortified beverage rather than whole food; sweetness comes from artificial sweeteners (sucralose and Ace-K); and a shake does not provide the fiber, chewing, or satiety of a real meal. Treat it as a supplement to real food, not a full nutrition plan. This is general information, not medical or dietary advice.

How does Kirkland Signature compare to Premier Protein?

On macros they are essentially identical — 30g protein, 160 calories, 1g sugar per 11.5 fl oz bottle, same 18.75g protein per 100 calories. Kirkland uses ultra-filtered milk (softer texture, closer to real chocolate milk); Premier uses milk protein concentrate + calcium caseinate (thicker, more shake-like). Premier adds a 24-vitamin fortification blend; Kirkland relies on the dairy-native micronutrient load. The single biggest difference is price: Kirkland at Costco is ~$0.043–$0.048 per gram of protein; Premier on Amazon is ~$0.078–$0.089 — nearly 2x. If you have a Costco membership and are not picky about vitamin fortification, Kirkland wins on value. See our Premier Protein shake nutrition guide for the full Premier breakdown.

How long do unopened Kirkland Signature Protein Shakes last?

The bottles carry a best-by date typically 3–5 months from the manufacture date because they ship refrigerated rather than shelf-stable. Store the whole case in the fridge at home. Unopened bottles are fine at room temperature for a few hours in a bag or lunch box, but should return to refrigeration for extended storage. Once opened, refrigerate and drink within 24 hours.

Bottom line: Costco’s Kirkland Signature Protein Shake delivers 30g of complete milk protein for 160 calories and 1g of sugar per bottle — the same headline nutrition as Premier Protein and effectively tied with Fairlife Nutrition Plan — at roughly half the cost per gram of protein. It is manufactured by Fairlife using the same ultra-filtered milk base as Core Power and Nutrition Plan, sweetened with the same four-sweetener stack (sucralose, Ace-K, monk fruit, stevia), and sold only in Costco warehouses and on Costco.com to members. If you have a Costco membership and are comfortable with artificial sweeteners, this is the single cheapest quality 30g RTD shake in America. For head-to-head comparisons with the widely-available alternatives, see our Premier Protein shake nutrition guide and Fairlife Nutrition Plan nutrition guide, or find the full budget ranking in our cheapest protein shakes 2026 guide. Browse more high-protein options in the full protein snacks directory.