Gannett Co. Chairman Allen H. Neuharth said yesterday that his firm's new national morning newspaper--approved by the board of directors earlier in the day, as expected--is aiming at a daily circulation of some 3 million within five years for a publication that will concentrate on sports, personal financial affairs and investing, and coast-to-coast features.

He also conceded that this first attempt in America to publish a mass-circulation, general-interest daily will reduce somewhat the annual growth in profitability that is a hallmark of Gannett in the newspaper and investment worlds.

The largest-circulation daily in the United States currently is the business-oriented Wall Street Journal, which sells 1.9 million copies a day. The financially troubled New York Daily News has the largest circulation of any general newspaper--1.48 million.

Speaking here to about 350 officers of the communications firm, publishers of Gannett's 85 newspapers, and executives from broadcasting and outdoor advertising subsidiaries, Neuharth confirmed that the Monday-to-Friday USA Today will begin publication in Washington next fall.

After local newsstand and vending-machine circulation has been established in the D.C. area, at a projected price of 25 cents a copy, USA Today will expand at planned intervals over six months into 15 of the nation's top 20 markets. When that cycle is completed, circulation will be expanded to the rest of the nation. Home and mail delivery is contemplated in some markets within the first six months.

USA Today will carry the same advertising and news content throughout the country, except for updated news stories in West Coast papers, and will be printed at numerous plants. The newspaper's staff will be based in Rosslyn, and the paper will be designed and printed at the Army Times Publishing Co. plant in Springfield, where a satellite dish already is in place for transmission of completed pages to other printing plants around the nation.

After Washington, the 14 metropolitan markets where USA Today will be circulated within the first six months are Baltimore (also printed here), Atlanta, Chicago, Denver, Detroit, Houston, Los Angeles, Miami, Minneapolis-St. Paul, New York, Philadelphia, Pittsburgh, San Francisco and Seattle. Except for the San Francisco area, where Gannett has dailies in Oakland, and in Westchester County north of New York City, Gannett currently has no major daily operations in these initial markets; the company's past newspaper success has come from local monopolies in small to medium-sized cities, in most cases.

Neuharth's announcement, which followed two years of research and publication of prototype editions, was greeted with a standing ovation from the all-Gannett crowd. USA Today will represent the largest new venture in Gannett's history -- requiring $50 million of capital or more over several years, according to Wall Street analysts.

Neuharth declined to specify how much of an investment is planned, but said only that Gannett's investment to date is "several million" dollars, and that costs of the new publication will be financed by the cash flow and profits of the company--which will generate revenues this year of about $1.4 billion and profits of more than $170 million.

Under currently projected economic conditions in 1982 and beyond, including the impact of recession, "we believe Gannett can continue its uninterrupted record of annual earnings gains while this new enterprise is established and developed . . . annual earnings gains--note I said gains--are projected to be somewhat lower than Gannett's 14-year average gains during the first couple of years of USA Today, but are projected to be sharply higher than that average thereafter," Neuharth asserted.

Gannett already is the nation's largest newspaper publisher in terms of daily circulation and number of papers. The Rochester, N.Y., company has been a Wall Street favorite because of an unbroken string of 14 consecutive years of record profits since it first began selling stock to the public in 1967.

Neuharth said Gannett research showed that the new daily could be successful as an "extra newspaper buy" for up to 5 percent of the nation's current 61 million daily newspaper purchasers, especially travelers.