Costco Reports Double-Digit Growth in August 2026 Sales. What That Means for COST Stock.

Costco (COST) shoppers kept spending through the last weeks of summer, and the numbers back it up. The warehouse giant posted another month of strong sales growth, giving investors plenty of reasons to watch Costco stock heading into Q4 2026.

The retailer's August results, covering the four weeks from Aug. 3 through Aug. 30, showed broad strength across regions and categories. Gas prices played a big role in the headline number, but even without that boost, Costco's core business kept growing at a healthy clip.

Here is what the latest report means for shoppers, the business, and anyone tracking Costco stock right now.

Costco has spent the past several quarters posting consistent comparable sales gains, even as shoppers wrestle with tariffs, inflation, and higher gas prices.

In its most recent quarterly earnings call, Chief Financial Officer Gary Millerchip said the company's third-quarter net sales rose 11.6% year-over-year to $69.15 billion. Comparable sales in Q3 rose 9.8%, or 6.6% once gas price swings and currency effects were stripped out. Executives credited a mix of factors for the strength, including growth in executive memberships, faster digital sales, and pricing moves meant to keep Costco competitive on everyday items like eggs and beef.

CEO Ron Vachris said on the call the company's strategy remains simple: be the first to lower prices and the last to raise them.

Costco's net sales for August came in at $23.70 billion, a 10% increase from $21.56 billion during the same period last year.

Total company comparable sales rose 8.4%.

By region, the U.S. led with a 9.0% gain, followed by other international markets at 9.5% and Canada at 4.0%. Digitally enabled sales, which include online orders, jumped 17.9%, continuing a trend of online shopping outpacing in-store growth.

Strip out gas prices and currency swings, and total comparable sales cooled to 5.4%, a more accurate read on core demand. Worldwide shopper traffic rose 2.5%, and U.S. traffic climbed 2.3%, suggesting more members are walking through the doors, not just spending more per visit.

Notably, Labor Day fell a week later in 2026 than it did in 2025, and management said that calendar shift dragged down August total and comparable sales by just under 75 basis points. Even accounting for that, total comparable sales excluding gas and currency effects still landed around 5.3%.