Like most Confessional poetry, Plath composed “Ariel” in free verse. Free verse is a general term given to poems that do not cohere to traditional poetic forms such as the sonnet or the villanelle. The form was pioneered by American poet Walt Whitman in the late 1800s and quickly became the dominant form in American poetry. Confessional poets such as Plath and contemporary Anne Sexton tended toward free verse because it allows a greater range of emotional expression compared to stricter forms. Like most free verse poems, “Ariel” is held together through atypical formal conventions.

“Ariel” consists of 11 stanzas. The first 10 stanzas are triplets, or stanzas of three lines. The poem’s final stanza consists of one line. This relatively consistent stanza length gives the poem a sense of structure. Each stanza focuses on one or two images, but those images—with the exception of the horse Ariel—rarely extend beyond their stanza. The poem’s segmented imagery gives the work a sense of fragmentation. The poem’s short stanza length and the speaker’s lack of articles and conjunctions in lines such as “[h]auls me through air— / [t]highs, hair; [f]lakes from my heels” (Lines 16-18) reinforce this fragmentation.