Question: what are the dimensions of a half size sheet pan?
Answer: Quarter sheet pans are typically 9 by 13 inches (a standard size for sheet cakes), half sheet pans are 18 by 13 inches (this is the size of most pans described simply as baking sheets) and full sheet pans are 26 by 18 inches (too big to fit in many home ovens, but the standard commercial size).