Not sure of the diameter. But the MS391 has a 25" bar on it for scale reference. There is another cottonwood in my creek that makes this one look small. I have a 15,000 lb. lift capacity forklift, and the ass end was bouncing with the one I used to make the display out of. But that was picking up most of the entire tree. When I drug it out of the creek to cut it up after felling it, I knocked my 076 super over upside down. It didn't hurt it, and it was just sitting there upside down idling perfectly like nothing was wrong...... :bang: