The chalmersia is an unnoticeable 13-limit comma with a ratio of 123201/123200 and a size of approximately 0.014 ¢. Named in honor of John H. Chalmers, it is the smallest 13-limit superparticular comma. Tempering it out equates 351/350 and 352/351, thus splitting 176/175 into two, and equates 385/351 and 351/320, thus splitting 77/64 into two – these are features highly characteristic of chalmers temperaments. In addition, it equates a stack consisting of a 729/512 tritone plus a 169/128 grave fourth with a stack consisting of a 25/16 augmented fifth plus a 77/64 minor third.
- As in Huygens-Fokker Foundation's interval list. There are other similar names that this comma sometimes goes by, including chalmersma, chalmersima, chalmerisma and chalmersisma, though at least some of these are mistakes.