All measurements are of the floor to the top of the head and when the figure is standing in the pictured pose. Assume a slight margin of measuring error.
Regular Kreons 1.75in - to give an idea of comparison
Regular Combiners - Devastator/Superion/other combiners 4.4in
Grimlock (dino) 2.1in
Metroplex/Fort Max/Scorponok 6.5in (with original head)
Omega Supreme/Omega Sentinel 4.8in
Optimus Prime Cab,Trailer/Ultra Magnus Cab,Trailer 2.5 in long, 1 inch high
Ravage, Steeljaw, Ramhorn 1.3in
Sky Lynx (Combined mode) 4.5in
Slag/Snarl (dino) 1.3in
Sludge (dino) 2.4in
Swoop (dino) 3.0 in long, feet to head, in "flight" mode
Trypticon 6.0in - Trypticon can stand tall or lean forward. It depends on how you position the legs and tail.
Ultra Magnus (robot)/Powermaster Optimus Prime Upgrade 2.1in
Voltron (combined) 6.2in