Interpreting Library of Congress (LC) Call Numbers

Each book in the Library’s collection has a call number. This number, derived from the Library of Congress (LC) Classification System, is comprised of several elements: a classification number (indicating the book’s subject or class), a Cutter number (creating an alphabetical arrangement by subdivision or author within the class), and certain additional information (e.g., year, volume #, copy #). Taken all together, these elements uniquely identify the item. Besides identifying the book, the call number also serves as an alpha-numeric code indicating its shelf location within the collection. The call number is referred to as such, because it can be used to request or call for a particular book.

Library of Congress (LC) call numbers are read from left to right and from top to bottom.

Letters in the first line of the call number comprise part of the classification number. They are in alphabetical order.


71 682 1930 1
.A30 .O73 .C63 .O53
1998 W56   v.1

Numbers in the second line of the call number comprise part of the classification number. They are in numerical order.

40.32 40.4 40.46 40.5
.A33 .R43 .I56 .W45
D56 2001 2001 1993

Letters and numbers in the third line of the call number comprise the Cutter number. Letters are in alphabetical order. Numbers are in decimal number order. A fourth line may have letters and numbers too. These will also be in alphabetical and decimal number order. It is important to remember that there is an "invisible" decimal point between the letter and the number.


76.9 76.9 76.9 76.9
.D3 .D32 .D337 .D4
A52 G725 N8 R9413
  1999   1991

One of the last lines of the call number may be a year. The year generally reflects the publication date.

The last line(s) of the call number may also have a volume number (i.e., v.1; t.2; Bd.3), a copy number (i.e., c.1; c.2; c.3), or both (i.e., v.1, c.1; t.1, c.2; Bd.3, c.3).