Abstract: The firearm magazine capacity limiter selectively limits the capacity of the magazine to comply with applicable laws or regulations. The capacity limiter has a rod including a follower contact end and an opposite attachment end that secures removably in a passage provided through a closure plate at one end of the magazine. The rod may have any length desired to limit the maximum capacity of the magazine as desired. Various attachment configurations are provided, including threaded attachment, quarter turn attachment, and sliding attachment via a capture flange on the attachment end of the rod. The capacity limiter may be used with detachable box-type magazines where the closure plate is the floor plate of the magazine, or with tubular magazines where the closure plate is the forward plug at the end of the magazine.