Length of the Book Index

• The length of a book index is generally determined by:



-	the number of pages available;
-	number of lines per page;
-	number of characters per line; and
-	total number of entries in the index.

• The number of pages set aside for the index can make a huge difference in the
  overall quality of an index.
  
  
• A general guideline for estimating the number of pages or length of an index is:
  
  

Estimates of Index Length From Indexing Books by Nancy C. Mulvany. pp. 65-67.
Type of Book		Percent of Index Pages	Entries per page
Mass market trade books	Light text, not heavy on details	2-5%	3-5
General reference books	Cookbooks Medical texts Academic texts Style manuals	7-8%	6-8
Technical Documentation I	General end-user manuals Introductory manuals Policy and procedures manuals Training manuals	10%	8-10
Technical Documentation II	Codes & regulations Service & repair manuals Specialized audience material Systems manuals Theory of operations	15%+	15+

Reducing the Index Length

• Reducing the size or length of a book index is something that should be done by
  the indexer, not the editor (unless the editor has extensive experience with indexes).
  
  
• The indexer is intimately aware of the index structure, and will have an "easier"
  time maintaining the structure, while reducing the entries.