Executives at Costco addressed how the retailer is addressing macroeconomic situations, including the cost of oil — plus its impact on gas sales — and tariff refunds.

Ron Vachris, CEO at Costco, said during the retailer’s Q3 earnings call that gas prices “are very much on members’ mind.” Moreover, they have had a “major impact” on Costco’s growth in gas sales. As a result, they have become a larger percentage of a member’s total spend in recent months.

“Against the backdrop of ongoing macro uncertainty, our focus is providing quality goods and services at the lowest possible price continues to resonate strongly with our members,” said Vachris. “Nowhere has this been more apparent in the third quarter than our gas business. As events in the Middle East have had a significant impact on product supply and gas prices, our focus, as always, is to be there for our members by staying in stock and offering the best value.”

Vachris referred to the U.S. and Israel’s war in Iran, which has led to supply chain disruptions regarding oil, increasing its price.

As of May 29, the price of a barrel of crude oil hovered around $86. It reached about $112 on April 7. For comparison, it was about $66 when the war began at the end of February, according to historical data from Trading Economics.

Costco’s fiscal Q3 began Feb. 16, less than two weeks before the war started. At the time, a barrel of oil cost about $66.

Costco is No. 7 in the Top 2000 Database. The database is Digital Commerce 360’s ranking of the largest online retailers in North America by their annual ecommerce sales. It’s also the fourth-largest Mass Merchant in the database.

Shifts in Costco traffic as fuel costs increased

Costco also saw a year-over-year increase in gas traffic during the quarter. Chief financial officer Gary Millerchip noted that Costco does not include gas traffic in its traffic figures. He said that generally speaking, “a little less than half” of members go into the warehouse when going to a Costco gas station.

“I wouldn’t say we’ve seen a dramatic change when you look at our results in the third quarter around traffic overall as a result of that,” Millerchip said. “We think that’s partly because a lot of members are increasing their frequency of visiting the gas station to top up in between what would have normally been a gap between getting the tank to empty because of the concern about what might the gas price be tomorrow.”

Costco members who purchase gas from the retailer generally visit its stores more frequently, he said. They also spend more at Costco overall than members who don’t purchase gas there and renew memberships at a higher rate.

“So we do think it’s a good, healthy barometer of long-term growth for the business as we continue to drive engagement in gas,” Millerchip said.

Impact of gas prices on Costco sales in Q3

Vachris said the result of oil’s market-price fluctuation was record-breaking volumes for Costco. Each month of its quarter set successive all-time volume sales records. The final five weeks of Costco’s fiscal Q3 became its top five weeks ever by the volume of gas it sold, Vachris said.

“The high consumer price sensitivity, which fueled these record volumes, also drove many members to use our gas stations for the very first time in the third quarter,” he stated. “We believe this will drive even greater loyalty with these members in the future as members who use our gas stations typically spend more with us in the warehouse.”

Millerchip said gas price inflation positively impacted Costco sales by about 2.2% in its fiscal Q3. In addition, he noted that Costco members also allocated a greater proportion of their total spending to gas in Q3.

“Because of the impact of higher gas prices, we felt it was important to continue to deliver more value for our members,” Millerchip said.

He said gas comparable sales were positive, with percentage growth in the high 20s. Millerchip attributed that to a price-per-gallon increase year-over-year as well as an acceleration in volumes.

However, Costco’s transportation costs also increased as a result of higher gas prices.

So far in its fiscal 2026, Costco has relocated two of its stores with one more planned for its current quarter. It’s relocating high-volume warehouses to larger locations with more parking and expanded gas stations. Vachris said that’s to provide a better member experience and drive higher volume in those warehouses.

How Costco is addressing tariff refunds

Vachris also said Costco is keeping track of multiple headwinds.

“We’re closely monitoring the longer-term inflationary impacts of higher oil prices as well as the future impacts of tariffs,” he said. “Our buyers continue to demonstrate their ability to adapt and are using their significant experience and expertise to try to reduce the impact on prices for our members. Our goal is to be the first to lower prices and the last to raise them.”

Vachris also said Costco has begun submitting its refund claims for the IEEPA tariffs. It’s using the process that U.S. Customs and Border Protection set up, he said.

Based on what other claimants have experienced, he said, Costco expects to receive refunds on approved claims on a rolling basis over the next two or three months.

“Our plan is to return to our members, in some form, the portion of tariffs that were passed on to them,” Vachris said. “How much we return and when depends on a variety of factors, including how much refund money we receive and when it arrives, as well as developments in the lawsuit filed against the company regarding the return process.”

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