Formula 


No. of leaf pages 
/ 
No. of index rows per page 
= 
No. of pages at next level 
If the number of index pages at the next level above is greater than 1, repeat the following division step, using the quotient as the next dividend, until the quotient equals 1, which means that you have reached the root level of the index:
Formula 


No. of index pages at previous level 
/ 
No. of nonleaf index rows per page 
= 
No. of index pages at next level 
Example 


157895/57 = 2771 
Index pages, level 1 
2770 / 57 = 49 
Index pages, level 2 
48 / 57 =1 
Index pages, level 3 