Kirkland vs Quest Protein Bars
The Kirkland Signature protein bar is widely called a Quest dupe, and the labels show why: the same milk and whey protein isolate blend, similar protein, similar calories, both sweetened with erythritol and stevia. They are made by different companies though, and the details differ flavour by flavour: fiber source, sugar, and which sweeteners appear where. Kirkland offers four flavours to Quest’s much larger range. Every number below is transcribed from the manufacturer’s nutrition label and verified by hand, so you can see exactly how close the Costco bar gets.
The numbers, side by side
Values are shown as the range across every flavour we have verified (4 Kirkland Signature Protein Bar flavours, 11 Quest Bar flavours). Winner is decided on the median flavour.
| Per bar | Kirkland Signature Protein Bar | Quest Bar |
|---|---|---|
| Protein per bar | 21–22gWinner | 20–21g |
| Calories per bar | 170–190 kcal | 170–190 kcalWinner |
| Protein per 100 kcal | 11.1–12.9gWinner | 11.1–11.8g |
| Sugar per bar | 2g | 0.5–2gWinner |
| Fiber per bar | 10–11g | 12–15gWinner |
| Fat per bar | 4–7gWinner | 6–9g |
| Bar size | 60g | 60g |
| Sugar alcohols | Erythritol | Erythritol |
| Other sweeteners | Stevia | Sucralose, Stevia |
| Protein sources | Milk Protein Isolate, Whey Protein Isolate | Milk Protein Isolate, Whey Protein Isolate, Caseinate |
Ingredients worth noting
Kirkland Signature Protein Bar
- Erythritol: A sugar alcohol that is close to zero calorie, does not raise blood glucose, and is better tolerated digestively than most polyols.
- Seed Oils: Refined oils high in omega-6 linoleic acid.
Quest Bar
- Erythritol: A sugar alcohol that is close to zero calorie, does not raise blood glucose, and is better tolerated digestively than most polyols.
- Palm Oil: Palm oil is pressed from the fruit of the oil palm; palm kernel oil comes from the seed inside that same fruit.
- Artificial Sweeteners: Synthetic zero-calorie sweeteners such as sucralose, acesulfame potassium and aspartame.
Where they rank
Kirkland Signature Protein Bar
- #1 of 10 in Protein Bars Without Maltitol
- #1 of 10 in Protein Bars Without Artificial Sweeteners
- #2 of 10 in Best Protein Bars
- #2 of 42 in Highest Protein Bars Per Calorie
- #2 of 9 in Best Protein Bars for GLP-1 Users
- #2 of 9 in Best Protein Bars for Ozempic Users
- #2 of 9 in Best Protein Bars for Mounjaro & Zepbound Users
- #4 of 10 in Protein Bars Without Seed Oils
- #7 of 10 in High Fiber Protein Bars
Quest Bar
- #2 of 10 in Protein Bars Without Sugar Alcohols
- #3 of 10 in High Fiber Protein Bars
- #3 of 10 in Low Sugar Protein Bars
- #3 of 10 in Protein Bars Without Maltitol
- #3 of 10 in Protein Bars Without Artificial Sweeteners
- #3 of 10 in Protein Bars Without Seed Oils
- #4 of 10 in Best Protein Bars
- #4 of 42 in Highest Protein Bars Per Calorie
- #4 of 9 in Best Protein Bars for GLP-1 Users
- #4 of 9 in Best Protein Bars for Ozempic Users
- #4 of 9 in Best Protein Bars for Mounjaro & Zepbound Users
Frequently asked questions
- Which has more protein per calorie, Kirkland Signature Protein Bar or Quest Bar?
- Kirkland Signature Protein Bar, with 11.4g of protein per 100 calories against 11.1g for Quest Bar (median across all verified flavours).
- Which has more fiber, Kirkland Signature Protein Bar or Quest Bar?
- Quest Bar, with 12–15g of fiber per bar against 10–11g for Kirkland Signature Protein Bar.
- Do Kirkland Signature Protein Bar and Quest Bar contain sugar alcohols?
- Kirkland Signature Protein Bar: Erythritol. Quest Bar: Erythritol. This comes from the verbatim ingredient list of every flavour we have verified.
Every Kirkland Signature Protein Bar flavour we have verified
Every Quest Bar flavour we have verified
Birthday Cake20g protein · 180 kcal · 11.1g / 100 kcal
Blueberry Muffin20g protein · 180 kcal · 11.1g / 100 kcal
Chocolate Brownie20g protein · 170 kcal · 11.8g / 100 kcal
Chocolate Chip Cookie Dough21g protein · 190 kcal · 11.1g / 100 kcal
Cookies & Cream21g protein · 190 kcal · 11.1g / 100 kcal
Double Chocolate Chunk20g protein · 170 kcal · 11.8g / 100 kcal
Lemon Cake20g protein · 180 kcal · 11.1g / 100 kcal
Mint Chocolate Chunk20g protein · 180 kcal · 11.1g / 100 kcal
Oatmeal Chocolate Chip20g protein · 180 kcal · 11.1g / 100 kcal
S'mores21g protein · 190 kcal · 11.1g / 100 kcal
White Chocolate Raspberry20g protein · 180 kcal · 11.1g / 100 kcalAll numbers on this page are transcribed from each manufacturer’s published nutrition label and verified by hand, then compared across every flavour in our database. If you are tracking a daily protein target, the Protein Pal app lets you scan either bar and log it in seconds. See everything from Kirkland Signature Protein Bar and Quest Bar, or browse all rankings and brands.
