The scores
Kirkland Signature: B (78/100) - Above average. Chicken first, chicken meal second, quality grains, and chelated minerals at warehouse pricing.
Blue Buffalo Life Protection: B (78/100) - Above average. Deboned chicken and chicken meal lead the formula, backed by brown rice, oatmeal, and barley.
How the ingredients compare
The top five ingredients are remarkably similar:
Kirkland Signature: Chicken, Chicken Meal, Whole Grain Brown Rice, Cracked Pearled Barley, Chicken Fat
Blue Buffalo: Deboned Chicken, Chicken Meal, Brown Rice, Oatmeal, Barley
Both foods lead with chicken and chicken meal - two named animal protein sources before any carbohydrate. Both follow with quality whole grains instead of cheap corn or wheat fillers. The main structural difference is that Kirkland puts chicken fat in position five, while Blue Buffalo uses oatmeal. Either way, you're looking at two formulas built on the same foundation: real chicken protein backed by digestible, nutritious grains.
This isn't a coincidence. Kirkland Signature is manufactured by Diamond Pet Foods, the same company behind Diamond Naturals and Taste of the Wild. These brands share supply chain infrastructure that enables quality ingredients at scale pricing - and Blue Buffalo's formula follows the same playbook.
Where Blue Buffalo pulls ahead
LifeSource Bits: Blue Buffalo includes cold-formed kibble pieces containing a concentrated blend of antioxidants, vitamins, and minerals. Whether this meaningfully outperforms a standard vitamin premix is debatable, but it's a supplemental feature Kirkland doesn't offer.
Omega-3 variety: Blue Buffalo includes flaxseed for plant-based omega-3s alongside its other fat sources. Kirkland also has flaxseed meal and fish meal, but Blue Buffalo's overall supplemental ingredient list is slightly longer and more diverse, including ingredients like glucosamine for joint support.
Wider availability: Blue Buffalo is sold at grocery stores, pet stores, and online retailers everywhere. Kirkland Signature requires a Costco membership and a trip to the warehouse. If convenience matters, Blue Buffalo wins by default. Shop on Amazon →
Where Kirkland Signature holds its own
The value proposition is the headline. A 40-pound bag of Kirkland Signature runs about $40 at Costco - roughly a dollar per pound. Blue Buffalo Life Protection typically costs $50-60 for a 30-pound bag, putting it at nearly double the per-pound price. For the same B/78 score, that's a massive price gap.
Kirkland also includes chelated minerals - zinc proteinate, manganese proteinate, and copper proteinate - which are bound to amino acids for better absorption than standard mineral salts. These are a hallmark of premium formulas that you'd expect in foods costing far more. Blue Buffalo uses a solid mineral package too, but Kirkland's chelated forms are a quiet advantage.
The ingredient list is also cleaner in one respect: Kirkland doesn't rely on pea protein, pea starch, or other pea-based ingredient splitting. Blue Buffalo includes pea protein further down its list, a mild plant-protein padding tactic. It's a minor point, but Kirkland's formula is more straightforward. Shop on Amazon →
The bottom line
These are functionally the same tier of dog food. Both score B/78, both lead with chicken and chicken meal, and both use quality whole grains. Blue Buffalo has slightly more supplemental ingredients and wider availability. Kirkland Signature has chelated minerals, a cleaner carb profile, and costs roughly half as much. If you're a Costco member wondering whether the house brand is as good as Blue Buffalo, the answer is yes - and you'll save a significant amount of money over the life of your dog. Read our full reviews of Kirkland Signature and Blue Buffalo for the complete breakdown.