How Costco Kirkland Grass-Fed Butter Has Changed In 2026

While we unpacked my latest Costco haul, my partner immediately noticed a difference in the butter package. "Is this thinner?" she asked, holding up the shiny green box. We weren't alone in noticing a change: Reddit was abuzz with others who realized Kirkland Signature's Grass-Fed Butter wasn't the same as the last time they shopped. "Kirkland grass-fed butter is a different shape now," wrote a user on the site. "Why make a change like this?" the poster continued. In the comments, another user got to the bottom of the alteration: according to Agriland, earlier this year Costco struck a deal with Irish dairy producer Tirlán, to make butter for the store's in-house brand.

This is a change from the previous provider of Kirkland's butter, New Zealand-based Westland Milk Products. The thinner box is longer — the same amount of butter, two pounds, is in both. The butter blocks look thinner but are also deeper, so they still are eight ounces per brick. In the Reddit comments, once people realized what was behind the shape change, they celebrated. "All of the major Irish butter manufacturers are the best in the world," wrote a Costco customer. To learn about the differences between Irish and American butters, read our guide on the subject.

Tirlán is the dairy co-op behind the Truly Grass Fed brand of butter, which is one of our recommended Kerrygold butter alternatives. The group is also the largest shareholder of Ornua, the owner of Kerrygold Butter, and supplies it with dairy. Costco sells Kerrygold for $4 more than the Kirkland Signature version, though prices vary by region.

Costco customers on Reddit are largely excited about the change in butter sources, but found one downside to the new packages. As one commenter put it, they were "salty about losing the tablespoon measurement lines." The solution proposed in the thread was to weigh your butter. A tablespoon of butter is roughly 14 grams. One person pointed out that weighing is better for baking, as "the lines often don't line up with the end of the stick."

Some preferred the older New Zealand butter. "I use this to make ghee and the Kirkland signature New Zealand butter was always amazing, [Kerrygold] for some reason doesn't turn out as good," wrote a disappointed Costco shopper. Some Irish farm groups also pushed back. According to the Irish Times, some groups feel the low price, store-brand butter marks a "race to the bottom." Tirlán supposedly attempted to get Ornua involved with the Kirkland Signature deal without success, per the Irish Independent.