The Washington Post Co. sold its Inside Sports magazine for at least several million dollars, according to the president of the company that bought it.

Although participants in the sale agreed not to reveal details of the agreement, Phil Syrdal, president of Active Markets Inc., which purchased the magazine, said the sale was "a several million dollar deal."

"It was much better than most people anticipated, because they didn't have to do some funny deal to give it away," Syrdal said of the agreement. The Post Co. put the magazine up for sale in November after 18 months of unprofitable operations.

Syrdal said last week that he plans to keep the magazine intact, although the staff will be reduced slightly.

"The magazine was 75 percent successful. The other 25 percent, we can provide," he said. "I absolutely love the product. It deserves to be the star of the show instead of the tail of the dog."

Active Markets is a privately held publishing company with headquarters in Bellevue, Wash. Its chief publication is Sports & Athletes magazine, with a paid circulation of 175,000. The average age of readers is 16. The company also publishes a magazine for younger readers called Young Athlete, which is published as the internal magazine of various youth sports associations.

Syrdal and his associates, which include a venture capital group Syrdal describes as the largest in the Pacific Northwest, purchased Young Athlete in late 1979. They renamed it Sports & Athletes and began producing the product that now bears the Young Athlete name. Inside Sports is the company's first major acquisition.

"We look at this magazine as our eastern beachhead," Syrdal said. "Our company has a lot of money, so we can do more acquisitions as we go along."