Obi-Wan ANH, Luke ANH/ESB, Vader ANH/ESB/ROTJ: 1 1/2" = 38 mm.
Most sabers in the prequels and Luke ROTJ (Hero version): around 1 3/8" = 35 mm.
Anakin AOTC: 1 1/4" ~= 32 mm.
Those are the most common diameters for the handgrip area on the sabers. Then various features can be narrower or thicker.