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3 Big Numbers is a weekly column that looks at a few key details from around the c-store industry.

While Costco has offered gas alongside some stores since 1995, news last week that it plans to open its first standalone gas station drew a lot of attention. The location in Mission Viejo, California, is expected to feature a 17,185-square-foot gas canopy with 40 fueling positions.

It’s unclear if Costco is planning to test more such locations, but if it does, the impact on c-stores, which sell about 80% of all fuel as things stand, could be significant.

In this week’s “3 Big Numbers,” we dig into why Costco’s latest fuel announcement is such a big one for the convenience retail industry.

The average difference between Costco fuel prices and market rates in California.

One of the main reasons so many people fuel up at Costco is the members-only pricing. Like the fueling sites offered at its warehouses, the standalone gas station will also require customers to be Costco members — which means it will likely share that pricing perk as well.

How much of a discount are we talking here?

The Oil Price Information Service (OPIS) reported that the average difference between Costco prices and market price for gas in California was 53 cents.

For customers seeking out lower prices, 53 cents per gallon is a big deal. Separate OPIS data showed that the average fuel markup in the U.S. was less than 40 cents in 2024, so if Costco starts putting more standalone gas stations in areas where a full store wouldn’t make sense, convenience retailers could face a big new threat.

The number of Costco gas stations offering expanded hours.

While its standalone gas station is the new, eye-catching model, Costco has also been making the gas stations alongside its stores more customer friendly by expanding fueling hours. The company announced in a March earnings call that its gas stations would be opening an hour early, and some would be closing an hour later as well.

“We did see some demand from the commuters, both at the early hours and the evening hours, so I think that that's going to be a real benefit to those folks,” said President and CEO Ron Vachris during the company’s Q2 earnings call in March.

The expanded hours were one of several factors credited with recently fueling two of its highest-ever weeks for gallons sold.

The number of paid Costco members.