How to Read Call Numbers
How our books are organized
The materials in our library are organized by the Library of Congress Classification system. A call number is the series of letters and numbers that tells you where a book belongs on the shelf. Read it from top to bottom, one part at a time. Each line follows slightly different rules which we’ll explain below. Book labels may split the parts across lines differently, but the reading order stays the same.
Follow this example
1738
.M35
1999
- Letters · alphabetically
- Number · low to high
- Letter, then decimal number
- Year · earliest to latest
Read the call number in four steps
Step 1
Start with the letters
Compare the first letter alphabetically, then the second letter if there is one. For example, L comes before LB, and LB comes before LC.
Step 2
Compare the number
Within the letter range, the numbers are arranged from low to high. For example, 1737 comes before 1738, which comes before 1739.
Step 3
Compare the letter, then the number
The next line, a letter-number combination, is called a Cutter number. These lines typically start with a period, followed by a letter and a number. Compare the letter first, then read all the digits after the letter as a decimal. For example, .M35 or .M357 comes before .M4.
Step 4
Compare the year
If all the earlier parts match, compare the year from earliest to latest. For LB1738 .M35, 1998 comes before 1999, and 1999 comes before 2000.
If your call number has more lines
Some call numbers have a second Cutter number before the year. Compare them one at a time, in the order they appear. Some call numbers may include volume information for serial publications. Move to the next part only when all the earlier parts match.
2844.1
.N4
B67
2000
LB: Compare the letters alphabetically.
2844.1: Compare the whole number, then the decimal. For example, 2844 comes before 2844.1, which comes before 2844.2.
.N4, then B67: Find the .N4 section first. Then move to the B’s within .N4. For each line, compare the letter, then the digits as a decimal. The 67 in B67 is read as .67 (point six seven).
2000: Compare the year only after all the earlier parts match.
Other labels may also include a volume or copy number. Compare those only after the preceding parts match.
Now find your book
Find your book in Discover and look for the library, shelving location, and call number. Use this information to find the right area of the library, then use the call number to find your book on the shelf.
Locations section in Discover
Library
The library to visit.
Shelving location and call number
The shelving location identifies the area inside the library. The call number helps you find the book on the shelf.
Where to find it
In Discover, this opens more location details, such as the floor and a map link.
This screenshot is an example. Check Discover for the library, shelving location, and call number of the book you want.
If you would like help locating your book on the shelves, Ask Us.