The outer dimensions of a finished book. Mass market paperbacks, for instance, are generally 4 1/4 inches by 7 inches. Picture books trim sizes vary tremendously—as does the cost associated with "odd" sizes.
The size of the pages in your book is the trim size. The second dimension is the binding edge. So, if it is an upright book, it is 5-1/2 x 8-1/2". Remember, if you measure a hardcover book, the "case" is larger and that is NOT the trim size. The trim size= page size. Note: Outside the US the bind dimension is often given as the first dimension. You can never go wrong using the words "upright" (portrait), or "oblong" (landscape). [Back
The trim size refers to the size (in inches) you selected for your book, such as 6 x 9, or 8 x 10. In a 6 x 9 book, the first number (6) is the width of the book. The second number (9) is the height, but if that sounds confusing, then think of the second number as the Spine number. If the spine is 9 inches, your book is 9 inches high.
The horizontal and vertical dimensions of a book. A book with an 8-by-10-inch trim size is 8 inches across and 10 inches high. A hardcover book has covers that extend beyond the pages, so book size and trim size aren't always the same.