I know many parents who are unsure of where their little one falls on the growth chart. You can always ask your pediatrician for a copy of this at their next check-up.
However, if you forgot or would like to keep track on your own, below are images of the CDC Growth Chars for Boys from birth to 36 months. The PDF version is attached at the end of the document for your convenience. This way, you can easily download and print the document.
For more information or help with using and interpreting these charts, check out this article on Understanding Growth Charts.
Boys_0-36mo head circumference