Costco August Net Sales Rise 9.9% as Comparable Sales Ex-Gas and FX Slow to 5.4%

COST posted a 9.9% rise in total net sales for August 2026, reaching $23.70 billion for the four-week retail month ended August 30, up from $21.56 billion a year earlier. That headline figure is total net sales, not a same-store measure, and it reflects the addition of new warehouses as well as existing-store performance.

On a comparable-sales basis, the picture is more nuanced than the headline suggests. Costco's total-company comparable sales rose 8.4% in August, but that figure includes the effect of higher gasoline prices and foreign-exchange movements. Excluding gas and FX, the more commonly cited comparable-sales metric, growth was 5.4% in August, continuing a deceleration from 8% in May, 7% in June, and 6.6% in July on the same adjusted basis . Digitally-enabled (e-commerce) comparable sales, by contrast, remained a standout at 17.9% in August, so the slowdown is concentrated in core in-warehouse comps rather than online.

Part of the August deceleration is a calendar effect rather than a pure demand signal: Costco said the shift of Labor Day to one week later in 2026 versus 2025 negatively impacted both total and comparable sales by a little less than 75 basis points. That does not erase the multi-month slowing trend, but it means August's comp number understates the underlying run-rate somewhat.

The divergence between double-digit total sales growth and slower comparable sales growth suggests new-warehouse openings and pricing/gas effects are doing more of the work than existing-store traffic and spending. This pattern is broadly consistent with the wholesale and big-box sector, where fuel-price swings and shifting consumer spending have complicated like-for-like comparisons in 2026.

Analysts will likely watch whether the comparable-sales deceleration continues into Costco's next fiscal year, how much of it is calendar noise versus a genuine plateau, and whether membership renewal rates, historically a stabilizing force for Costco's revenue, hold up. Investors should weigh Costco's ability to sustain profitability as comparable-sales growth moderates, while also watching whether digitally-enabled sales and ancillary revenue such as Kirkland private-label products continue to offset the slower pace of in-warehouse comp growth. This is market analysis, not investment advice.

Related Stocks

• COST