I dont know,I carried 3 posts 6x6 by 14 feet long by myself to my truck about 100 feet away and loaded them in the bed--they were heavy,but not more than 100 lbs I'd guess--no way I could lift and walk off with one weighing much more than that..these were not pressure treated and they were native pine lumber though..
Of course the type of wood will make a difference too--oak or cherry would weigh twice or more than a pine timber the same dimensions..
Also trying to hold a post upright in a hole only 4 feet deep with a lot more standing up above ground is very difficult,the leverage against you makes it feel much heavier..I put a pipe 30 feet high in the ground to mount an antenna on before,that thing almost took my arms off when I started tilting..
First thing I did when erecting tall posts was to drive two stakes in the ground at 90 degrees apart about 8 feet away,and had the 2x4 braces already attached to the stakes ,with a nail driven most of the way in the other end,so I could hammer the braces on with one hand while holding the post steady--its a hard job to perform alone,a few posts I had to use guy ropes to hold them up while I made sure they were plumb before bracing them..