Washington area supermarket clerks and meat cutters yesterday accepted a new contract that will give them raises of $2.25 an hour over the next three years, plus cost-of-living increases and improved retirement benefits.

The ratification vote heads off a potential strike and means business as usual today for major supermarkets in the District of Columbia and the suburbs, most of which were closed yesterday for a union meeting.

The raises of 75 cents an hour each year amount to 8.5 percent the first year for clerks and total 25 percent for the next three years.

The new contract will boost the pay of experienced full-time checkout clerks from their present $8.73 an hour to $10.98 by 1983 and will hike the wages of journeymen butchers from $9.63 to $11.88, supermarket chain spokesmen reported yesterday.

The higher wages for food store workers will put added pressure on food prices, which have risen sharply in the past year. But the supermarkets may not be able to pass on all the cost to consumers now, because price competition has been unusually intense lately in the washington area.

Washington and Baltimore supermarket chains negotiate labor agreements jointly with a panel of unions representing workers in the two cities. The old contract expired Saturday night.

The new three-year pact was approved by Washington workers yesterday morning in a meeting at the District of Columbia Armory. Baltimore workers have yet to vote on the pact, but supermarket spokesman said stores there are expected to be open today.

Washington supermarket workers are represented by Local 400 of the United Food & Commercial Workers Union, the organization created by the merger of the Retail Clerks International Association and the Amalgamated Meatcutters and Butcher Workers union.

Union officials could not be reached for comment yesterday; representatives of major chains provided details of the new contract, which makes local supermarket employes among the highest paid in the country.

Currently full-time checkers with two years of experience earn $8.73 an hour -- just under $350 for a 40-hour work week. The new contract's 75 cents per hour per year raises will immediately boost their pay to $9.48 an hour -- $379 a week. Next year another 75 cent raise will mean $10.23 an hour -- $409 a week; the following year the base pay goes to $10.95 an hour -- $439 a week for clerks.

For meat cutters who now earn $9.63 an hour -- $385 for 40 hours -- the new pact means raises to $10.38 or $415 a week, $11.13 or $445 a week, and $11.88 or $475 a week.

The new contract also provides cost-of-living adjustments in March 1981 and March of 1982, plus an increase in the employers' contribution to employes' retirement programs, a Safeway spokesman said.

The sharp increase in labor costs comes at a time when supermarket profits are already under heavy pressure and competition in the always-competitive industry is ever more fierce then usual. Profits were down 33 percent in the first half of the year at Giant Food Inc., the biggest supermarket chain in the Washington market. Giant's earnings slipped to $4.85 million (99 cents per share) from $7.86 million ($1.57) for the 24 weeks ended Aug. 2.

Giant said part of the severe decline in earnings was due to a decision to freeze prices on about 400 items for more than four months. The price freeze was prompted by increased competition from cut-rate food markets, appealing to consumers who are trying to hold down their grocery bills.

Both Giant and Safeway -- the No. 2 chain in the market -- have announced plans to open their own discount food operations to compete with the food warehouses and so-called "box stores" that display goods in their shipping cartons.