The Washington Post Co. said yesterday that it has agreed to sell its Florida cellular telephone operations to McCaw Communications Cos.

The Post Co. would not reveal the sale price, but a calculation of the price paid by McCaw for each potential subscriber indicated that it was in excess of $200 million.

The sale of the Florida properties is expected to produce an after-tax gain of about $110 million. The sale also marked the end of the Post Co. involvement in the cellular telephone business.

"The decision to sell our Florida cellular interests was difficult, but we are pleased that McCaw Communications, which has other cellular operations in Florida, should be able to provide growth opportunities for both the employes and the systems," said Post Co. President Richard D. Simmons.

Under the terms of the sale, which must be approved by the Federal Communications Commission, the Post Co. will sell its 100 percent interest in the Miami-Fort Lauderdale cellular system to McCaw, along with its 13 percent interest in the Palm Beach system.

Sources familiar with the transaction said that while the Post Co. was not looking to leave the cellular business, the price offered by McCaw was higher than that paid in other cellular deals and was just too good to pass up.

Some Wall Street analysts have said recently that cellular telephone properties have the potential to be worth $70 per head of population. Sources familiar with the transaction said McCaw agreed to pay the Post Co. in excess of $70 per head for the operations, which could offer service to about 3 million Floridians.

In addition to the Florida deal, the Post Co. has announced plans to sell its 20 percent interest in the Washington-Baltimore cellular telephone system to Southwestern Bell Corp. and its 18 percent interest in Detroit cellular to a unit of Pacific Telesis Group.

Washington Post Co. Chairman Katharine Graham has said the sale of those properties is expected to produce an after-tax gain of about $50 million.

In 1985, the company reported an after-tax gain of about $4 million on the sale of other cellular operations, bringing its total after-tax gain on cellular to about $164 million.