A U.S. penny is 19 mm across. Various websites claim the Southern Hemisphere’s smallest frog is about 9.8 millimeters, Brazilian Gold Frog (Brachycephalus didactylus). This frog beats the Brazilian Gold Frog by about 5 mm – this frog is only approximately 5 mm. The (previously????) smallest frogs of the Northern Hemisphere is the Cuban Eleutherodactylus iberia, which can be two-tenths of a millimeter smaller, and Eleutherodactylus limbatus, of which fully mature adults as small as 8.5 mm have been found.
Alas, it seems this frog beats those by half. I’ll post some more pictures and video eventually, but it is here in Florida in the United States and is much smaller. A record? I don’t know. (Found by Lexi Riley, Maddie Johnston and me).