Arrow FOC: What Front-of-Center Really Does for Bowhunters
FOC is the percentage of your finished arrow’s weight that sits ahead of center. It changes how the arrow steers, how it holds line in wind, and how it recovers off the string. It does not turn a 400 grain arrow into a bone crusher. This page shows how to calculate it, what number to aim for, and where high FOC helps or hurts.
How to calculate FOC
Measure your finished arrow tip to nock throat (call that L). Balance it on a straight edge and measure tip to balance point (call that B). FOC in percent = ((B minus L divided by 2) divided by L) times 100. A 29 inch arrow balancing at 17.5 inches from the tip: (17.5 minus 14.5) divided by 29 = 0.1034, or 10.3 percent FOC.
Target FOC by discipline
| Use case | Target FOC | Notes |
|---|---|---|
| 3D and target | 8 to 11 percent | Flatter trajectory, longer sight range |
| Whitetail, deer sized game | 11 to 14 percent | Balanced flight and penetration |
| Elk, moose, bear | 14 to 18 percent | Ranch Fairy / Ashby camp; heavier front for bone |
| Extreme heavy | 19 to 30 percent | EFOC/UEFOC; specialty builds only |
Most hunting brands publish their arrows at 10 to 12 percent FOC out of the box with a 100 grain point. To get to 15 percent you usually need a brass or steel insert and a 125 to 150 grain broadhead.
Where high FOC helps
Crosswind stability improves once you pass 12 percent because the mass concentrated up front acts like a weathervane rudder in reverse. Penetration into hair, hide, and rib bone improves at 15 percent and above once total arrow weight is also 500 grains or more. Broadhead flight forgiveness also gets easier because a nose heavy arrow recovers faster from paradox.
Where high FOC hurts
Trajectory drops. A 500 grain arrow at 15 percent FOC losing 4 fps versus the same weight at 10 percent will drop an extra 1.5 inches at 40 yards. Extreme FOC arrows (over 20 percent) also nose dive past 50 yards, which pushes stump shooters and 3D archers away from that build.