Federal spending cuts approved by Congress will raise school lunch prices and curtail some programs in the Fairfax county schools, but not as much as local officials had feared.

That is the assessment given the county School Board last night by its budget staff, which predicted that President Reagan's cutbacks will require increasing school lunch prices, on the average, by 25 percent -- or 15 cents. Local school officials had predicted that the price of school lunches would double next year.

Federally funded local programs, in particular courses for the handicapped and reading classes for the disadvantaged, are scheduled to lose $636,000. The school board originally anticipated losing $1.5 million in this area.

"The good public an thank Misters Helms and Perkins for that little bit of luck," said Assistant Superintendent Bill Shadle, referring to Sen. Jesse Helms (R-N.C.) and Rep. Carl D. Perkins (D-Ky.).

Under the original Reagan plan, the 127,000-student school system would have lost all but $1 million of its current $6.2 million in federal food aid next year. Proposals submitted by Helms and Perkins -- and approved by the two houses of Congress last month -- would cut county federal funds only by $2.5 million, restoring more than half the anticipated cuts. Total cuts in the federal school lunch program amount to nearly $1.5 billion of the current $6 billion budget.

Fairfax Country is the first school system in Northern Virginia to announce proposed lunch-price increases.

Although the price increases are not as extreme as expected, Shadle pointed out that the reduction in federal funds would still hit some Fairfax County parents hard. Nearly 70 percent of students in the county school system participate in the lunch program and under the proposal facing the board all increases in cost would be borne by the buyer. No local funds are used in financing the program.

"It's just one more thing to budget for. If I had three or four kids in the school system and had to ante up an extra 15 cents each day it would hurt," Shadle said. Students participating in the free-lunch programs, he said, would not be directly affected by the budget cuts, but could be hit under new eligibility requirements to be released at the end of this month.

The school staff also recommended cutting back a subsidized breakfast program in operation at 63 schools to 27 schools where 50 or more students participate in the program.

In other federally funded programs, school officials said a cutback of $636,000 will mean 225 students from low-income families would not be able to participate in the Title 1 reading program and that handicapped students would be affected by a reduction in teaching staff and materials. Programs for the handicapped are scheduled to lose $261,000. Earlier this year, the school board and the county Board of Supervisors voted not to replace the loss of any federal funds with local money.

At its meeting last night, the school board reelected its chairman, Ann P. Kahn of the Providence district. She defeated Anthony Lane of the Lee district on a 6-to-4 vote. Mary Collier of the Dranesville district was re-elected vice chairman.