This study investigates the variation of the Farsi vowel formants – F1 and F2 – among Persian-American heritage and immigrant speakers in Oklahoma, a topic which has been under-investigated. The participants were a group of 20 Persian adult immigrants (ten males and ten females) and 20 US-born Persian-American heritage speakers of Farsi (ten males and ten females). Data were gathered in the form of acoustic audio recordings of a 150-word word list carefully pronounced by the participants. A lexicon was created for the purpose of forced alignment, and vowel formants were extracted using DARLA. The vowel plots showed substantial similarity among all participants to the Farsi monolingual speakers’ in Iran regarding the back vowels /u/, /o/ and /ɒ/. However, the front /i/ and /e/ sounds were a bit more back than that of the monolinguals. In regard to /æ/, both groups of female Persian immigrants and female Persian heritage speakers showed similarity to that of the monolinguals; however, male Persian immigrants and male Persian heritage speakers had a relatively raised /æ/.