Front of Center (FOC) is the percentage of an arrow's total length that sits in front of the physical center point. A higher FOC means more weight up front, which improves stability, penetration, and flight consistency — especially at hunting distances.
The NFAA-recommended hunting range is 10–15%. Many big-game hunters push toward 15–25% for maximum penetration on tough animals.
Measure from the throat of the nock (where the string seats) to the balance point. The balance point is where the arrow rests perfectly on a single finger.
Front of Center (FOC) tells you how much of your arrow's weight sits forward of its midpoint. Enter the arrow length and the measured balance point, or switch to component weights, and the calculator returns your FOC percentage with a hunting suitability rating. Everything runs in your browser and nothing is stored.
Worked example: a 29 inch arrow balances 17.5 inches from the nock throat. The midpoint is 14.5 inches, so the balance point is 3 inches forward. 3 divided by 29 gives an FOC of about 10.3 percent.
| FOC | What it means |
|---|---|
| Under 7% | Rear heavy. Flight is often unstable, especially with broadheads. |
| 7 to 10% | Low. Works for target and 3D, marginal for hunting. |
| 10 to 15% | The common hunting range. Good stability and penetration balance. |
| 15 to 25% | High FOC. Strong penetration, often used for elk, moose and other big game. |
| Over 25% | Extreme. Needs a stiffer spine and a drop in speed is likely. |
The easiest way to add FOC is a heavier point or broadhead, for example 125 grain instead of 100 grain. You can also add weight to the front with brass or steel inserts, or take weight off the back with a lighter nock and lighter vanes. Adding front weight makes the shaft act weaker, so recheck your arrow spine after any change.
A higher FOC usually means a heavier arrow, which lowers speed a little and increases penetration. Our guide to kinetic energy and FOC shows how arrow weight and speed trade off, and the arrow weight guide covers total grain weight by game animal. Once your arrow is final, enter its measured speed in the sight tape generator and verify the printed marks at the range.
Most bowhunters aim for 10 to 15 percent FOC. Hunters who want extra penetration on large game often go to 15 to 20 percent, as long as the arrow still flies cleanly and the sight tape is verified.
Rest the finished arrow on a ruler edge or a single finger and slide it until it balances. Measure from the throat of the nock to that point, then enter it in the calculator with the arrow length.
It can. More front weight lowers arrow speed slightly and changes trajectory, so verify your sight tape at the range after any change to point weight, inserts or total arrow weight.