The example illustrates the computations on a table that contains 9,000,000 rows:
The sum of fixed-length column sizes is 100 bytes.
The sum of variable-length column sizes is 50 bytes; there are 2 variable-length columns.
The table has two indexes:
A clustered index, on a fixed-length column, of 4 bytes
A composite nonclustered index with these columns:
A fixed length column, of 4 bytes
A variable length column, of 20 bytes
Different formulas are needed for allpages-locked and data-only-locked tables, since they have different amounts of overhead on the page and per row:
See “Calculating table and clustered index sizes for allpages-locked tables” for tables that use allpages-locking.
See “Calculating the sizes of data-only-locked tables” for the formulas to use if tables that use data-only locking.