How Costco’s Same-Store Sales Measure Retail Performance
What comparable sales include
Costco’s comparable sales help separate the performance of established operations from growth created simply by opening more warehouses. The company’s September 2025 release reported five-week comparisons for U.S., Canadian, and other international operations, alongside a separate digitally enabled measure.
That distinction matters because total revenue growth can come from several sources at once: additional locations, changing prices, currency movements, fuel sales, and shifts in customer demand. Same-store sales, also called comparable sales, offer a narrower view by comparing activity across an existing base rather than crediting every new warehouse as organic progress.
According to Costco, comparable-sales measures are supplemental information and do not replace net sales reported under U.S. generally accepted accounting principles. Investors should therefore read them beside reported revenue, not as an alternative measure of the company’s total financial results.
For a practical example, imagine a long-standing warehouse serving the same community while a new location opens nearby. Total company sales may rise because the new site adds revenue, but the older warehouse’s comparable sales indicate whether its existing customer base is spending more or visiting more often.
Why a sales increase needs context
The September comparison also requires care because Costco identified unusual factors affecting the prior-year period. The company said last year’s sales benefited from consumer activity associated with Hurricane Helene and port strikes, making a simple year-over-year comparison less straightforward.
Costco reported total comparable-sales growth of 5.7% for the five weeks ended October 5, 2025. Excluding the effects of gasoline-price changes and foreign exchange, the reported total was 6.0%, illustrating how external factors can alter the headline reading without changing the underlying customer experience.
Those adjustments do not make the unadjusted figure meaningless. They answer a different question: the reported result describes sales as recorded, while the adjusted result attempts to isolate performance from specific price and currency effects.
For readers evaluating retail performance, the useful approach is to compare definitions before comparing numbers. A metric is most informative when its period, business coverage, and adjustments are clear, especially when a company changes how it groups digital orders.
Signals behind the September results:
- Five-week comparison period ended October 5, 2025
- Total comparable-sales growth reported at 5.7%
- Adjusted comparable-sales growth reported at 6.0%
- Prior-year disruptions affected the comparison base
These distinctions establish the measurement framework; the regional results show where the reported momentum was strongest.
Reading Costco’s Regional Same-Store Sales Results
Regional differences behind the headline
Once the comparison period is clear, regional results add useful detail because Costco’s markets do not move in lockstep. For the five weeks ending October 5, 2025, the company reported comparable-sales growth of 5.1% in the United States, 6.3% in Canada, and 8.5% in other international markets.
On a basis excluding gasoline-price and foreign-exchange impacts, the reported figures were 5.0% for the United States, 9.3% for Canada, and 7.5% for other international markets. The adjusted figures change the apparent regional ranking, a reminder that commodity prices and exchange rates can meaningfully affect reported comparisons.
According to Costco’s release, consolidated net sales for the retail month were $26.58 billion, up 8.0% from $24.62 billion in the comparable period a year earlier. That total-sales increase and the comparable-sales figures describe related but different aspects of the business: one measures overall net sales, while the other focuses on established operations.
For an analyst, a regional split can help frame further questions rather than deliver instant explanations. If one market grows faster, the figures alone do not establish whether the cause was stronger store traffic, a higher average transaction value, a different product mix, or local conditions.
Using the numbers without overreading them
The release gives a snapshot, not a complete account of customer behavior. Costco does not provide a traffic-versus-ticket breakdown in the supplied September results, so assigning the growth to one driver would go beyond the evidence available here.
Consider a household that makes one extra warehouse visit before a holiday weekend. That could raise transaction counts, while a larger basket could lift average transaction value; both can support sales, but the reported comparable-sales percentage does not distinguish between them.
The company also operates in markets with different currencies and consumer conditions. A comparison that excludes foreign exchange can help isolate operating performance, while the unadjusted number remains relevant to the sales actually recorded in each reporting currency.
Analysts can organize the available figures before drawing conclusions. Keeping the reported and adjusted measures side by side discourages false precision and makes it easier to identify where additional disclosures would be useful.
Regional figures and their stated basis:
| Market | Reported comparable sales | Excluding fuel and foreign exchange |
|---|---|---|
| United States | 5.1% | 5.0% |
| Canada | 6.3% | 9.3% |
| Other international | 8.5% | 7.5% |
| Total company | 5.7% | 6.0% |
The table reproduces Costco’s five-week September 2025 comparisons; the adjusted column excludes the specified gasoline-price and foreign-exchange effects. With regional context in place, the next analytical question is how Costco defines digital activity within comparable sales.
Costco’s E-Commerce Expansion and the Digital Sales Measure
Why the digital definition changed
Regional reporting explains where comparable sales increased, but Costco’s digital measure changes how analysts should understand the channels behind those sales. In its October 2025 release, the company replaced its e-commerce comparable-sales label with “digitally-enabled” comparable sales.
According to Costco, the revised measure includes sales delivered to members that begin through a digital device, whether the order is fulfilled by a warehouse or a distribution center. It also includes Costco Travel, so the measure covers more than parcels shipped directly from a conventional online storefront.
This wider definition reflects an omnichannel business: members can begin shopping on a website or mobile app and receive goods through different parts of Costco’s operating network. An online order fulfilled from a nearby warehouse, for instance, is digital in how it starts even though the warehouse remains central to fulfillment.
That boundary matters when comparing periods. A change in the label and scope can make the latest figure less directly comparable with older figures described as e-commerce comparable sales, even if the underlying business activity has not changed at the same pace.
What online sales growth does and does not show
Costco reported digitally enabled comparable-sales growth of 26.1% for the five-week September period, or 26.3% excluding gasoline-price and foreign-exchange impacts. These figures were substantially higher than the companywide comparable-sales measures, but they represent a differently defined channel measure.
The data supports the conclusion that digitally initiated sales were growing quickly during that reporting period. It does not, by itself, reveal the online channel’s share of total sales, its profitability, order frequency, or the relative contribution of delivery, warehouse pickup, and travel bookings.
Some supplied secondary material lists $13.1 billion in e-commerce net sales for costco.com but does not establish the precise reporting period or accompanying definition. Without that context, the number should not be combined with the September release or presented as a verified current-year result.
For investors, digital expansion is best assessed through consistent definitions and multiple measures. A strong growth rate can indicate member adoption, while total sales, fulfillment costs, margins, and repeat purchasing are needed to assess the quality and durability of that growth.
Digital sales measures compared:
| Measure | What the supplied definition covers | What it cannot establish alone |
|---|---|---|
| Digitally enabled comparable sales | Member sales initiated digitally and delivered through warehouses or distribution centers, plus Costco Travel | Profitability or channel share |
| Warehouse comparable sales | Comparable sales from established warehouse operations, as described in the supplied materials | Digital order economics |
| Costco.com net sales | Net sales attributed to the company’s website, where a period is specified | Performance of every online service |
| Total net sales | Company sales reported for the stated period | Organic growth without further comparison |
As digital orders become part of the same member journey as warehouse visits, their operational economics deserve as much attention as their growth rate.
How Store Traffic, Basket Size, and Fulfillment Shape Growth
Separating visits from spending per visit
Costco’s comparable-sales results describe revenue movement, but they do not identify the precise mix of customer visits and basket size. Retailers often examine store traffic and average transaction value separately because either can increase sales, and the distinction helps explain what may be changing in customer behavior.
If more members visit during a period while spending roughly the same amount each time, traffic is the likely contributor. If visits remain steady but shoppers purchase more items or higher-priced goods, average transaction value may be the larger driver; the supplied Costco release does not quantify either component.
Gasoline further complicates interpretation because fuel-price changes can affect reported sales even when the number of gallons sold does not change in the same way. Costco’s adjusted comparable-sales figures explicitly remove gasoline-price effects, providing another view alongside the unadjusted result.
A careful reader therefore treats traffic, transaction value, and price effects as questions to investigate rather than facts already proven by a headline percentage. This discipline is especially useful when a strong digital growth rate appears beside more moderate warehouse comparisons.
Connecting online ordering to warehouse operations
Digitally initiated orders can rely on physical infrastructure, including warehouses and distribution centers, rather than operating as a separate business detached from stores. Costco’s revised definition makes this connection visible by counting qualifying digital orders according to how they begin, not only where they are fulfilled.
That arrangement can create practical advantages for members who want to browse remotely and receive products through a nearby fulfillment network. It can also require labor, inventory coordination, delivery capacity, and technology, meaning that faster online sales do not automatically translate into higher margins.
Costco’s release provides no detailed breakdown of fulfillment expense or digital profitability. Its supplied materials also state that the e-commerce business has a lower gross-margin percentage than warehouse operations, but without a dated margin figure, readers should avoid assigning a specific financial impact.
Operational questions become more useful when grounded in observable disclosures: which services the metric includes, how sales are classified, and whether the company reports consistent period-to-period comparisons. Those questions help distinguish genuine expansion from a change in accounting presentation.
Operational questions for digital growth:
- Which member orders qualify as digitally initiated sales
- How warehouse and distribution-center fulfillment are classified
- Whether comparable periods use consistent metric definitions
- What the company discloses about costs and margins
Those operating details connect sales growth to the costs and risks that investors must assess next.
Investor Questions for Costco’s Retail Performance
Growth quality, margins, and comparable periods
Costco’s September results offer evidence of sales growth, but evaluating its quality requires more than comparing percentages. Investors can start by separating total net sales from comparable sales, then distinguish the digitally enabled measure from warehouse-focused comparisons and note every adjustment.
According to Costco’s release, the company operated 914 warehouses at the time, including 629 in the United States and Puerto Rico and 110 in Canada. The company also listed e-commerce sites in the United States, Canada, the United Kingdom, Mexico, Korea, Taiwan, Japan, and Australia, showing the geographic breadth of its physical and digital footprint.
That footprint can support growth through new locations and wider digital access, but it also means the reported total combines different markets and channels. Comparable sales help isolate established operations, while reported net sales show the wider scale of activity during the period.
Investors should also remember the company’s warning that comparable-sales figures are supplemental rather than replacements for GAAP net sales. A sound analysis uses both, alongside disclosures about costs, margins, capital spending, and member behavior when available.
Risks and a disciplined reading framework
Costco identified risks that can affect future results, including economic conditions, inflation, exchange rates, competition, consumer spending patterns, employee costs, energy prices, tariffs, and privacy or security breaches. These factors can influence both warehouse visits and digital ordering, although the September release does not quantify their future effects.
A disciplined reading avoids treating a single month’s growth rate as a forecast. The five-week period included an unusual prior-year comparison base, and the new digitally enabled measure broadened the scope beyond a narrow website-sales interpretation.
Analysts can use a short sequence of checks before drawing a view. First confirm the period and metric definition; next compare reported and adjusted figures; then separate warehouse and digital measures where possible; finally ask whether the company provides evidence on profitability and repeat demand.
For a member deciding whether to shop in a warehouse or online, the figures offer a different kind of context: they show Costco’s business is serving customers through both channels, while leaving service quality and individual value to the shopper’s own experience.
Checks for interpreting Costco’s results:
- Confirm the reporting period and number of weeks
- Separate total net sales from comparable-sales growth
- Read adjusted results beside unadjusted figures
- Track changes in the digitally enabled definition
- Seek margin and fulfillment disclosures before judging returns
These checks keep the analysis anchored in reported evidence, while leaving room for later disclosures to clarify how digital expansion contributes to durable growth.
Source: Costco Wholesale Corporation, “Costco Wholesale Corporation Reports September Sales Results,” GlobeNewswire, October 8, 2025.
