How to sing Amazing Grace in your key
Amazing Grace spans 12 semitones (D4 to D5 in its usual key), 35 notes. That's an octave or less, so it fits most voices once it's in the right key.
Words
Amazing grace! How sweet the sound
That saved a wretch like me!
I once was lost, but now am found,
Was blind, but now I see.
Finding your key
A song is in your key when its highest note sits at or just below the top of your comfortable range. Measure your range, then move the melody so its top note (D5 here) lands one or two semitones under your easy top. Singsteady does this for you and scores every note as you sing.
1779 words (John Newton); tune “New Britain”, 1829. Melody and words are in the public domain. Notes transcribed from the score in Wikipedia, “Amazing Grace” (score).