information:highlighting, stylistic:style_transfer, linguistic:paraphrasing
Vocal category, size and range

Although she is generally described as a dramatic coloratura soprano, "categorizing Sutherland's voice has always been extremely difficult, both the size and the sound present definitional problems Aside from singing some roles popular among coloratura sopranos, Sutherland's voice could not be more different."

In a 1961 profile in The New York Times Magazine, Sutherland said she initially had "a big rather wild voice" that was not heavy enough for Wagner, although she did not realise this until she heard "Wagner sung as it should be."

Regarding the size of Sutherland's voice, Opera Britannia praise "a voice of truly heroic dimensions singing bel canto. It is doubtful if any soprano in this repertoire has fielded quite so much power and tone as Dame Joan, and this includes Callas and Tetrazzini. The contrast with other sopranos who sing the same roles is appropriately enough stupendous, with rival prima donnas producing small pin points of sound as compared to Sutherland's seemingly endless cascades of full tone." In 1972, music critic Winthrop Sargeant describes her voice "as large as that of a top-ranking Wagnerian soprano " in The New Yorker. French soprano Natalie Dessay states, "She had a huge, huge voice and she was able to lighten suddenly and to take this quick coloratura and she had also the top high notes like a coloratura soprano but with a big, huge voice, which is very rare."

Sutherland's vocal range extended from G below the staff (G) to high F (F), or high F-sharp (F ♯), although she never sang this last note in a public performance.