Locate the metal plate on the side of the chainsaw that contains the model and serial numbers. The plate is black and riveted to the body of the tool.
Read the first two digits of the serial number; this indicates the year of manufacture. For example, 2010 is a "10" and 2011 is a "11."
Read the next two digits (the third and fourth in line) to find the week of manufacture. For example, serial number 110123456 was made in the first week of 2011.
Make a note of the year of manufacture for future reference. Some products have the full year of manufacture included at the start of the serial number followed by a hyphen -- "2005-1234567," for example.