"All I Want for Christmas Is You" is played at an original tempo of 150.162 beats per minute. According to the sheet music published at Musicnotes.com by Sony/ATV Music Publishing, the song is set in common time and in the key of G major. Carey's vocal range in the song spans from the note of G3 to the high note of A6. Carey wrote the song's lyrics and melody, while Afanasieff arranged and produced the piece with synthetically created computerized equipment.