Sight adj= Desired-change-in-impact * Sight Radius/Distance to target, all in inches
For my rifle, the sight radius (or distance between front and rear sight) is 28 inches. If I want to hit 4 inches higher at 100 yds (or 3600 inches), sight adjustment would be 4*28/3600" or .031", or approx. 1/32". I could either remove that much metal off the front sight, or raise an adjustable rear sight by that much.
For 4" lower impact, lower the rear sight or put in a taller front sight. To move impact point to the left, move rear sight to the left or front sight to right, etc.