What is "Trim"?
"Trim" is the area of the album that will be cut / trimmed by album companies after printing. Most albums are printed in full spreads, and trimmed only on the spreads' outer edges. The amount the lab trims on the outer edges of the spread should be entered into the Left/right and Top/bottom fields in the Custom album size setup:
Remember that the value inputted indicates how much will be trimmed from each side. In the screenshot above 0.125 inches would be trimmed on each side. This means that if the printed spread is 20x10 inches, the final size after trimming will be 19.75x9.75 inches.
Note: The values inputted into Trim fields do not affect Output Dimensions. The size of the exported spreads depends only on what is inputed into Output Dimensions fields. Trim values are used for displaying the red trim line during album design and proper image centering. For further clarification please read Difference between trim & bleed.
Difference Between "Trim" & "Bleed"
Although some labs use the two interchangeably, the terms "trim" and "bleed" refer to different things. To learn the differences and what information you should input into SmartAlbums, please read Difference between trim & bleed.
Some album companies print albums in single pages (instead of full spreads), and later trim not just the outer edges, but also the inner edges of each page. If the print lab you use trims inner page edges, please read Inside trim & bleed fill.