Threads caption character counter
Short answer
Koldflux has not read a Threads page that states a caption length, so this page does not state one. The counter measures in all three units and sets no pass mark.
The counter
Characters, UTF-16 code units and UTF-8 bytes, because the three disagree on every non-ASCII character and a limit written in one of them cannot be compared with text counted in another.
0 characters | 0 UTF-16 code units | 0 UTF-8 bytes
No denominator, because the Threads caption pages read on 2026-10-08 state no length limit. All three measurements are shown because the three units disagree on every non-ASCII character, and a platform that documents its limit in one of them cannot be compared against text counted in another.