Use the formulas in this section to help you estimate the future sizes of the tables and indexes in your database. The amount of overhead in each row for tables and indexes that contain variable-length fields is greater than tables that contain only fixed-length fields, so two sets of formulas are required.
The process involves calculating the number of bytes of data and overhead for each row, and dividing that number into the number of bytes available on a data page. Each page requires some overhead, which limits the number of bytes available for data:
For allpages-locked tables, page overhead is 32 bytes, leaving 2016 bytes available for data on a 2K page.
For data-only-locked tables, 46 bytes, leaving 2002 bytes available for data.
For the most accurate estimate, round down divisions that calculate the number of rows per page (rows are never split across pages), and round up divisions that calculate the number of pages.