President Reagan yesterday formally recommended a 4.8 percent annual pay raise for the government's 1.4 million white-collar workers, including 300,000 in the Washington area.

The October raise would be the smallest since a 4.8 percent increase in 1973 and about half the size of last year's increase.

Reagan, saying his decision would save the taxpayers $4.5 billion a year, rejected government salary data showing it would take an average 15.1 percent increase to equalize pay with comparable jobs in private industry.

The president said his proposal is based on total worker compensation -- pay and fringe benefits -- and contended that federal fringes are generally higher than in the private sector.

A White House spokesman said, in explaining the reason for the choice of the lower figure, "There was a feeling that federal workers had to share the burden."

Federal unions denounced the proposed raise as politically motivated and a further slap at civil servants who are being hit with budget and job cuts. Kenneth Blaylock, president of the American Federation of Government Employees, the largest federal union, said the proposed raise is far less than the rise in the cost of living and is "not only unfair, but totally insensitive to government workers who suffer from inflation like everybody else."

Reagan first proposed the 4.8 percent figure in his budget earlier this year. But under the law governing federal pay raises he had to either go along with a full catch-up with industry -- the 15.1 percent reported by the Labor Department, Office of Management and Budget and Office of Personnel Management -- or submit an alternate plan to Congress by midnight yesterday. Yesterday he chose the latter course.

In theory, Congress has 30 days to veto the 4.8 percent figure and order the full 15.1 percent raise. In fact that is unlikely since the Budget Reconciliation Act set a 4.8 percent limit on 1981 raises for white-collar federal civilians.

With the new pay raise, the starting salary of a Grade 5 secretary or beginning professional, for example, would go up from $12,266 to $12,854 a year. Grade 9, which now has a range of $18,585 to $24,165, would have a range of $19,477 to $25,318. Grade 13, the beginning level for most supervisory positions, would rise from its current range of $32,048-$41,660 to a new range, $33,586-$43,666.

Because Congress has established a salary ceiling, a Grade 14 worker in the top (10th) pay step now earning $49,229 will not get the full 4.8 percent raise, but will go up only to the $50,112.50 level.

The pay raise will boost the monthly civilian federal payroll in the Washington area to about $770 million. The raise does not affect postal workers, blue-collar (wage board) employes and retirees. Military personnel will get the raise unless Congress approves pending legislation that would give them an October raise of 14.3 percent.

White House sources said Reagan had been urged by several top advisers to skip any government pay raise this year, reckoning that it would play well politically, and show the administration's determination to further cut federal spending.

Federal unions' attacks on the White House for firing 12,000 striking air traffic controllers meant the unions had no IOUs to collect. But aides said Reagan insisted on the 4.8 percent raise as representing a fair catch-up.

In 1980, President Carter told Congress the system used to weigh federal pay with industry was tilted unfairly in favor of government workers. He proposed a "total compensation" concept to compare government wages, retirement, vacation and other benefits of government workers with industry.

Under such a system, Carter said the 1980 federal raise would be about 5 percent. However, just before the election, under heavy pressure from union leaders, Carter approved a surprise 9.1 percent raise. It was still short of a full catch-up with industry, but enough to soothe some union chiefs.

The Reagan administration has proposed similar changes in the pay-fixing law. Congress has endorsed the end result -- a 4.8 percent raise this year instead of the 15.1 percent due under the current formula -- but has not yet acted on the changes themselves. Yesterday Reagan made another pitch for those changes.

The biggest pay raise white-collar federal workers ever received in one shot was a 15.9 percent boost in 1945, just as World War II was ending. There was no raise from 1952 to 1955.

During the 1960s, when the government got into the catch-up-with-industry business, federal workers sometimes got two raises in one year. One of the largest such combinations was a 9.1 percent boost in July 1969 and an additional 6 percent that December.

After the 4.8 percent raise in 1973, federal white-collar workers got 5.5 percent in 1974; 5 percent in 1975, 5.2 percent the next year, 7 percent in 1977, 5.5 percent in 1978, 7 percent in 1979 and 9.1 percent in 1980.

Staff writer Dan Balz contributed to this report.