Wow, Nick! That's pretty substantial. I can growl down to a D2 and on a very foggy day, a bit lower, but a G4 is well beyond my range.

So what are you? Pretty hard to pin down. Your range is very much that of an operatic bass, bass-baritone or baritone, although a few operatic parts call for a baritone to be able to hit an Ab above the G4 (Tonio the clown in the Prologue of I Pagliacci—final note of the aria). Whether you are a bass, bass-baritone, or baritone would depend on voice quality—how deep or light your voice sounds, and that would take a voice teacher to diagnose.

Doubtful that you are a tenor with that range. I'm not sure where they got the tenor range on the chart I linked to (I hadn't really looked at it closely), but most operatic tenors are required to have a two-octave range from the C below middle C to the C above. Choral tenors a bit less, but for an operatic tenor, that high C is considered to be "the money note." When Placido Domingo first started singing, they had him classified as a light baritone, but he had the high notes, so he opted to be a tenor, which has worked pretty well for him.

I never did get a solid diagnosis as to whether I'm a bass or a bass-baritone, but there's very little difference. I sing the bass range, but I'm not quite as "rumbly" as most basses.

So range isn't the whole story.

I really envy you your high notes!

Don Firth