Arrow FOC (Front of Center) Calculator
Calculate the Front of Center percentage of an arrow to optimize flight stability and penetration for target, 3D, or hunting archery.
Results
What is it?
Front of Center (FOC) measures how far forward of the arrow's midpoint the balance point lies, expressed as a percentage of total arrow length. A higher FOC makes the arrow more stable in flight but can reduce glide distance. The sweet spot depends on your shooting discipline: target/3D archery: 10�15%, hunting: 12�19%, extreme penetration: 25%+.
How to use
Measure your complete arrow (with point, insert, nock, and fletching in place) from the nock groove to the tip. Then balance the arrow horizontally on a thin edge or fingertip and measure from the nock groove to the balance point. Enter both measurements.
Example scenario
A 28-inch arrow balanced at 17 inches from the nock: center is 14 inches, FOC = (17 - 14) / 28 � 100 = 10.7%. This is on the lower end of the hunting range. To increase FOC, switch to a heavier point (125-grain vs. 100-grain) or add weight to the insert.
Pro tip
Heavy broadheads significantly raise FOC. If your FOC is too high (>25%) for target shooting, your arrow may plane into the wind and reduce accuracy. Conversely, a low FOC (<8%) can cause erratic flight � the arrow "fishscales" in the air. Test different point weights in 25-grain increments to find the optimum.