Oh boy! Another fit method discussion! I get height by heel-on-pedal. Problem is that's not really precise because it depends on being able to detect hip rocking. My method is super precise - I set my saddle height by being able to pull back hard at the bottom of the pedal stroke. Which sound totally imprecise, but everyone's different in the way their muscles are attached and how they work, so I think it's as good as anything. For first heel-pedal and then climbing hard at a moderate cadence and trying to produce power at the bottom of the stroke. My impression is that, at least for me, that's a very narrow range, maybe 2mm.

Setback, I like my hands to be fairly light on the bars, but some weight in them. That has me with my saddle all the way back, but I think that's because it's 52cm and there's something funny with the seat tube vs. toe strike.

Reach - I like a lot of reach, my upper arms at 90° to my torso with my forearms horizontal when on the hoods.

So I go setback - height - reach. Using this method means my thighs will hit my lower ribs when I'm all the way down, which limits my aero, but OTOH it's comfortable for a 24 hour ride and I'd rather have the latter.

No formula, but oddly enough I'm exactly at KOPS. Whatever.