Analysts polled by Thomson Reuters expected, on average, a rise of 3.7 percent from the Issaquah, Wash., wholesale club operator.
Revenue at stores open at least a year is considered a key indicator of retailer health because it leaves out results from locations that have opened or closed in the last year.
Costco said revenue from established locations rose 3 percent in the United States and 2 percent internationally.
Excluding the impact of gasoline prices and foreign currencies, Costco said revenue from stores open at least a year climbed 5 percent.
Total revenue from the five-week period that ended July 1 climbed 6 percent to $9.18 billion.
Costco has 605 warehouse locations, 438 in the United States and Puerto Rico, 82 in Canada, 32 in Mexico, 22 in the United Kingdom, 13 in Japan, eight in Taiwan, seven in Korea and three in Australia.
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