Extent/Space Calculator: a tool to estimate the space occupied by archival holdings based on the exterior size of your containers. UNLV. "Rebel Archives Calculator: for cubic and linear feet"

I really like this tool because it is easy to use, containing a pre-built list of standardized archival boxes, AND it also allows you to insert custom sizes to calculate containers that don't match an existing size (a custom box or maybe materials that aren't in archival boxes yet that you received as a new donation and want some data about). A great way to figure out how much space your collections occupy and their shelving needs! I use this tool in video 3 (DACS Identity Elements: P2) of my Creating Access through Archival Description workshop course (23-minute mark discusses Extent).