Approximately:
30" at 400 yards
70" at 500 yards
120" at 600 yards
No simple formula unless it's printed on the side of the ammo box.
A lot of things need to be taken into account such as Ballistic Co-efficient, bullet weight as well as muzzle velocity.
Most reloading manuals will have ballistics tables but your gun also needs to be sited in at a certian distance which you did not give us. I guessed at 200 yards and a muzzle velocity of 3200ft/sec using a 55grain FMJ.
Like it was stated before, the tables are just starting points...each individual gun will be slightly different.
