Question: what is the size of a half sheet pan?
Answer: U.S. sizes A half sheet pan is 18 in × 13 in (460 mm × 330 mm); quarter sheets are 9 in × 13 in (230 mm × 330 mm). The half sheet is approximately the same size as mass-market baking sheets found in supermarkets, and the quarter sheet is a common size for rectangular, single-layer cakes.