written in the key of e minor, "hello" is a midtempo rock song with guitar chords and its hand claps. according to the sheet music published by kobalt music publishing, clarkson's voice range featured in the song spans from a to e. jarett wieselman of "omg! insider" noted that its chord progression is similar to katy perry's single "last friday night (t.g.i.f.)" (2011), a track also written by mckee.