To calculate Forward of Center (FoC) arrow balance for a particular arrow set-up (mounted with head/broadhead of choice):

  1. Measure overall shaft length from bottom of nock to back of head, for example 30″
  2. Divide that length in half (15″) and mark the shaft’s linear center at that point
  3. Balance the shaft on the edge of a ruler or other thin support and mark that spot
  4. Measure the distance from linear center mark to balance point mark, for example 5.5″
  5. On the chart, plot overall shaft length (30″) along the top, horizontal column
  6. Plot FoC measurement (5.5″) on the left, vertical column
  7. Where these two columns meet in the chart is percentage FoC for that arrow set-up, in this example 18.33%

Up to 12% is standard FoC; 13% to 19% is high FoC; while 20% and above is extreme and what we’re wanting in a big game arrow system. Generally, the higher the FoC, so long as arrow flight remains perfect, the greater the penetration potential.

FOC Chart