Skip to Main Content

Understanding Call Numbers

Understanding Call Numbers

Have you ever wondered how library books are assigned their places on the shelves? Did you know that the call number -- the number placed on the spine of the book -- is a code which provides valuable information about the book? This page will provide an introduction to understanding and using library call numbers.

What are Call Numbers For?

Each book in the library has a unique call number. A call number is like an address: it tells us where the book is located in the library. Call numbers appear like this, on the spines of books:


and like this, in the online catalog:
LB2395 .C65 1991

Note that the same call number can be written from top-to-bottom, or left-to-right.

University/College Library at BCC Central Campus, like many academic libraries in the U.S., uses Library of Congress Classification for call numbers. This system uses a combination of letters and numbers to arrange materials by subjects.

Reading Call Numbers

Read a call number by sections, line-by-line. Each section is part of the "code".

LB -- Read the first line in alphabetical order:
A, B, BF, C, D ... L, LA, LB, LC, M, ML ...

2395 -- Read the second line as a whole number:
1, 2, 3, ...45, ...100, 101, ... 1000, ... 2000, ...2430, 2431, 2432

.C65 -- The third line is a combination of a letter and numbers.
Read the letter alphabetically: A, B, C, D, E, ... Y, Z
Read the letter as a decimal.
e.g. .C65 = .65
e.g. .C724 = .724

1991 -- This is the year the book was published.
Chronological order: 1979, 1985, 1991, 1992 ...

Putting Call Numbers in Shelf Order

To understand how call numbers are put in order in Library of Congress Classification, again look at each section of the call number. These call numbers are in the correct order:

1. LA2301 .M37
2. LB2327 .M3
3. LB2327 .V53 1990
4. LB2328 .B37
5. LB2328 .C34
6. LB2328 .C55
7. LB2328 .C554 1982
8. LB2395 .C65 1987
9. LB2395 .C65 1991

Could you see why the call numbers were arranged in this order? Shelf-order can be confusing at first. Here is the same list of call numbers, with explanations of how they were put in order:

1. LA2301 .M37
2. LB2327 .M3 (LB comes after LA)
3. LB2327 .V53 1990 (Both start with LB2327, V comes after M)
4. LB2328 .B37 (2328 comes after 2327)
5. LB2328 .C34 (C comes after B)
6. LB2328 .C55 (Both start with LB2328 .C, decimal .55 comes after .34)
7. LB2328 .C554 1982 (Decimal .554 comes after .55)
8. LB2395 .C65 1987
9. LB2395 .C65 1991 (Same call numbers except for date: 1991 comes after 1987)

What Does the Call Number Mean?

Remember that Library of Congress Classification arranges materials by subjects. The first sections of the call number represent the subject of the book. The letter-and-decimal section of the call number often represents the author's last name. And, as you recall, the last section of a call number is often the date of publication.

Title: What You Need to Know About Developing Study Skills, Taking Notes & Tests, Using Dictionaries & Libraries
,Author: Marcia J. Coman.
Call number: LB2395 .C65 1991
Let's crack the code by examining the sections of this call number:

LB2395 = subject of the book: Methods of Study in Higher Education
.C65 = Coman, the author's last name
1991 = the publication year


Why is this important to know? Because books are classified by subject, you can often find several helpful books on the same shelf, or nearby. For example, within the same call number LB2395, there are other guides for college study.

LB2395 .C6 1960 - A Student's Guide to Efficient Study, by Luella Cole
LB2395 .C65 1991 - What You Need to Know ..., by Marcia J. Coman
LB2395 .L447 - Keys to College Success, by Minnette Lenier
LB2395 .O54 1983 - A Successful Student's Handbook, by Rita Phipps

Since Library of Congress Classification arranges materials by subjects, knowing the letter(s) for your subject area gives you a place to start browsing the shelves. Which letters represent your subject? View the Library of Congress Classification Table.

Location Prefixes

When a call number looks like the examples above, (e.g. LB2395 .C65 1991), the book is shelved on the third floor of University/College Library. Some call numbers, however, are preceded by a location prefix.
Ref AG243 .G87 1992 -- The Ref prefix indicates that this book is shelved in the Reference Collection.

Location prefixes mean that book is shelved in a special place, and may have loan restrictions. Check for a location prefix before trying to find the book in the library. University/College Library uses the following location prefixes:

Prefix Collection U/C Library Location Loan Period
[Blank] General Collection 2nd floor, 3rd floor, and 4th floor 21-day loan
Career Career Collection 1st floor, Reference Area 21-day loan
CLC Children/Juvenile Collection 4th floor, Children Section 21-day loan
Leisure Best Seller Collection 1st floor, Reference Area 14-day loan
Oversize Oversize -- a big book! 4th floor 21-day loan
[Blank] Magazine/Journal Collection 2nd floor, 3rd floor, and 4th floor (shelved with General Collection) Library-Use Only
Leisure Newspapers and Magazines 1st floor, opposite coffee shop Library-Use Only
REF Reference Collection 1st floor, Reference Area Library-Use Only
Res Reserve Collection 1st floor, Circulation Area Library-Use Only
Video Audio/Video Collection 2nd floor, Learning Resources Center Library-Use Only


For more information about call numbers and finding library materials, ask your librarian.