how many oysters in a peck? and a bushel?

a bushel of oysters contains around 100 or so oysters; there are 4 pecks in a bushel, so a peck of oysters is usually about 25 oysters, depending on the size of the oysters (and the quality of the oyster bar!).
Pecks In A Bushel
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RE:

how many oysters in a peck? and a bushel?
1 dry pint = 1/64 bushel = 1/2 dry quart

1 dry quart = 1/32 bushel = 1/8 peck

1 peck = 1/4 bushel

1 U.S. bushel (basic unit of dry capacity in the United States) = 2,150.4 cubic inches

1 imperial bushel (basic unit of dry capacity in some Commonwealth nations) = 2,219.4 cubic inches
It depends on the size of the oysters. You buy them by the pound at the fish market.