Federal employes will be given a 7 percent pay raise in October, rather than the 5.5 percent that had been planned, administration sources said last night.

The new plan is expected to be announced this morning by John P. White, deputy director of the Office of Management and Budget, and Alan K. Campbell, director of the Office of Personnel Management, at a White House briefing.

Kenneth T. Blaylock, president of the American Federation of Government Employes, said he was "very pleased" with the planned announcement.

Blaylock, reached by telephone in San Francisco, said "we have been working for some time to convince the president that we should have comparability with the wage guidelines that are in place for the private sector."

Private industry is asked to adhere to a 7 percent voluntary wage guideline.

"The only posture I could take was to accept nothing less than the private-sector guidelines now in place," Blaylock said. "We will carry our load in the inflation fight, but we don't think we should be made to carry more than our fair share."

Increasing inflation and the new wage and price guideline options being considered by the White House for the private sector which would exceed the present 7 percent guideline were the two major reasons behind President Carter's decision to increase the raise for federal workers, sources said. Carter made his decision late Wednesday, after aides flew to Camp David with option papers.

The 7 percent wage guideline has been broken repeatedly in the private sector, irking government employes who have been forced to accept smaller wage increases.

And the cost of living has risen faster than expected, leading the Council on Wage and Price Stability to work up new more realistic wage guidelines for the private sector to compensate for inflation.

The 7 percent federal pay raise would be considerably below the 10.4 percent that government officials have said would be needed for federal employes to catch up with the earnings of their white-collar counterparts in the private sector.

That large a pay boost would cost $5 billion to $6 billion.

Carter had said for months that he planned to hold the federal workers' pay increase to 5.5 percent as part of his administration's anti-inflation program.

He held federal pay increases to 5.5 percent last year, despite the fact that aides said the employes were due an average 8.4 percent boost.

More than 360,000 workers in the Washington area will be affected by the raise, which goes into effect during the first pay period after Oct. 1.Nationwide, more than a million white-collar government workers will be affected.

Congress has 30 days to consider the proposal, and either the Senate or the House could overturn it and instead order a larger increase. Such an action is considered unlikely.

Sources said Congress probably will endorse the proposal by doing nothing about it.

The next major hurdle for the administration is likely to come when the wage and price council issues new guidelines for private industry.