While most girls stop growing taller around age 15 or 16, some continue to grow until age 16 or even slightly beyond, it is not generally past the age of 18. This information is supported by the CDC growth chart which shows a height plateau between 15 and 16 years.
Several online sources corroborate this: Quora discussions https://www.quora.com/Can-a-girl-grow-taller-after-18 and https://www.quora.com/Is-it-possible-for-a-woman-to-continue-to-grow-after-18 reveal anecdotal evidence of some women experiencing minor growth after 18, but these cases are exceptional. Reddit threads (https://www.reddit.com/r/short/comments/xpyxb2/did_anyone_here_grow_after_18/, https://www.reddit.com/r/NoStupidQuestions/comments/16swgwq/can_i_still_grow_taller_at_18_do_you_know_any/, https://www.reddit.com/r/tall/comments/3hh6lh/how_much_did_you_grow_after_18/, https://www.reddit.com/r/selfimprovement/comments/1chk1ns/is_there_any_way_i_can_grow_taller_after_18/, https://www.reddit.com/r/AskMen/comments/1b4pzl6/how_long_do_men_continue_to_grow_after_hs/) also discuss individual experiences, highlighting the rarity of significant growth beyond 18. The consensus across these platforms points to the overwhelming likelihood that significant height growth ceases before 18 for females.
While exceptions exist, the general rule is that significant height increase after 18 is uncommon for girls.
