The Washington metropolitan area has the third highest per capita income in the country - $8,454 per person - according to figures released Saturday by the U.S. Department of Commerce.

The Washington area's per capita income was exceeded only by Anchorage, Alaska with $10,739, a figure that reflects the infusion of billions of dollars to build the Alaska pipeline, and by Bridgeport-Stamford-Norwalk-Danbury, Conn., a wealthy bedroom community outside New York City with a per capita income of $8,902. Just behind Washington are San Francisco-Oakland with $8,142 and Reno, Nev., with $8,273.

In the latest available figures - for calendar year 1976 - the Washington metropolitan area, with its concentration of federal workers, held its place as one of the most affluent areas in the country. The Washington area also ranked number three in the 1975 income figures behind the same two areas.

Within the metropolitan area, Arlington County had the highest per capita income - with $11,962 - followed by Montgomery, $9,967; Fairfax, with $8,696; the District of Columbia, with $8,081; Loudoun, with $7,710 and Prince George's, with $7,034. Falls Church, which is counted as an independent city by the Commerce Department, had a per capita income of $14,488. Alexandria's per capita income was $9,929 adn Fairfax City's was $9,173.

A slightly different measurement - of household income - released earlier last week by Sales and Marketing Management magazine and based on 1977 data, showed that household income was highest in Fairfax County. That survey, which included the country's 10 largest urban areas, ranked this area number one in household spending income.

Per capita income differs from household income measurements because the income earned by a household - usually a family - is divided by the number of persons in that household to derive the income per person. As a result, a household with a high income but with a large number of persons in it could show a lower per capita income than households with fewer members.

Although the Washington metropolitan area is one of the most affluent in the country, several individual counties elsewhere have higher per capita incomes, according to the figures compiled by the Commerce Department's bureau of economic analysys. The county with the highest per capita income is Loving, Tex. - with $15,710 per person - followed by Roberts, Tex. - with $12,944. Wichita, Kan. - with $11,690 per capita - follows Arlington closely.

The other metropolitan areas in the top 10, according to the Commerce Department figures, are: Nassau-Suffolk (New York), 8,046; Newark, N.J., 8,024; Chicago, 7,785; Midland, Tex., $7,701 and San Jose, Calif., 7,686.

Of the 10 metropolitan areas with the lowest per capita income, five are in Texas-Bryan-College Station, El Paso, Brownsville-Harlingen-San Benito,Laredo and McAllen-Pharr-Edinburg. Their per capita incomes range from $3,338 to $4,733.

The New York metropolitan area - with a per capita income of $7,568 - ranked 13th among metropolitan areas. Los Angeles with 14th with $7,529 per capita.