You can use the following steps to estimate the amount of space required to store data in a table:

1. Calculate the space required for the heap or clustered index following the instructions in Estimating the Size of a Heap or Estimating the Size of a Clustered Index.
   
2. For each nonclustered index, calculate the space required for it by following the instructions in Estimating the Size of a Nonclustered Index.
   
3. Add the values calculated in steps 1 and 2.