The numbers
A cord is defined by volume: 128 cubic feet of wood that is “ranked and well stowed”, meaning the pieces lie parallel, touching, and stacked tight. The usual way to picture it is a stack 4 ft high, 4 ft deep and 8 ft long (4 × 4 × 8 = 128).
Watch out for “face cord”
A face cord or rick often describes one row of logs. The depth matters: a stack 4 ft high × 8 ft long × 16 in deep occupies about one third of a full cord. Ask for the stack’s dimensions and volume so you can compare quantities.