Read the Call Number

Example of a Library of Congress Call Number in the catalogTo use the Call Number to find the book on the shelf, you need to know how to read it.

To begin, start with the first letter or letters - in this case, BT.Call Number

Understand the Shelving Arrangement

Books are arranged in alphabetical order so BT is near the end of the B section. B comes first, then BA, and so on. Some letters may be skipped. As you can see in the graphic below, for example there is no BB nor BE.



arrangement of Call Number Ranges of Bs



Head to the Section of Shelves

When you are in the BT section, look at the next part of the Call Number - the numbers on the next line - in this case 216.3.

end cap of book shelves


Read this as a whole number. So go to the BT 200 section and keep moving until you find the BT 210s section. Then find the BT 216 section. Often the number you are looking for will land between a range of other numbers on that shelf. As you can see in the image above, in this case, BT 216 falls between BT 198 and BV 600.2, so this is the shelf you will find your book.


Find Your Book

Once you find the area with books assigned the Call Numbers BT 216, look at the next part of that line of your call number, .3. Read ".3" as a decimal, so look through BT 216s for BT 216.1, then BT 216.2, then BT 216.3.

book shelf location

Then look at the next line and read ".G37" alphabetically, then read the "37" as a decimal. So find BT 216.3 .Gs (G comes after B, as in our example image above). If there were a book with the Call Number BT 216.3 . G36, it would come right before our book on the shelf.

Usually that is enough, but if you need to, you can continue reading any additional lines of your Call Number in the same way. The next line of our Call Number is a year, and these are arranged chronologically. So if there were another book with the Call Number BT 216.3 .G37 2020, it would be on the shelf right after our book.

For more detailed information on finding a book in the Library, see How to Find a Book on the Shelves.

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