FOC stands for Forward of Center balance point. This measurement results from the relative weights of the components used in the arrow: shaft, insert, head, fletching and nock. A properly balanced arrow measurements of 7 to 10%.
Pick a tree near the target and draw an imaginary line straight out to a point at eye level. This is the distance needed for the chart. In this example, 20 yards. A guesstimated angle of 45 degrees will require an aiming distance of 14.1 yards even though the straight line distance is 28 yards. Remember, it doesn't matter if the angle is up or down, the answer is still the same.
|Angle (up or down)|
Distance in yards
(NOT Straight Line Distance)