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FOC (Front of Center) Calculator.

Calculate an arrow's front-of-center percentage from its length and balance point.

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Set your values

Results update as you type.

FOC (%): 10

FOC (%)

0.000000
balancePoint: 18

balancePoint

0.000000
arrowLength: 30

arrowLength

0.000000

Results update automatically as you type.

Use Cases

Tune Your Hunting Arrows

Determine if your hunting arrows have sufficient front weight for better penetration and stability. Adjust point weight or arrow length to achieve desired FOC.

Example: A 28-inch arrow with a balance point 16 inches from the nock has a FOC of 14.3%.

Compare Arrow Setups

Quickly compare different arrow builds (length, point weight, etc.) to see how FOC changes, helping you choose the best configuration for your bow.

Example: Compare a 27-inch arrow with a 100-grain point vs. a 125-grain point to see FOC difference.

Frequently Asked Questions

What is arrow FOC and why does it matter?
FOC (Front-of-Center) is the percentage of the arrow's total weight that is located in the front half. It affects arrow flight, stability, and penetration. A higher FOC (10-15%) is often preferred for hunting, while a lower FOC (7-10%) may be used for target shooting.
How is FOC calculated?
FOC is calculated by finding the distance from the arrow's center to its balance point, dividing by the total arrow length, and multiplying by 100. The formula is: FOC% = ((Balance Point - (Arrow Length / 2)) / Arrow Length) * 100.
What is the ideal FOC for my arrow?
The ideal FOC depends on your shooting style and purpose. For hunting, a FOC of 10-15% is common for better penetration. For target archery, a FOC around 7-10% may be preferred for flatter trajectories. Experiment to find what works best for your setup.

Tips & Common Mistakes

Tips

  • Measure arrow length from the bottom of the nock groove to the end of the shaft (excluding the point).
  • Find the balance point by balancing the arrow on a thin edge (like a knife) and mark the spot.
  • For consistent results, use the same arrow components (nock, insert, point) when measuring.
  • A FOC between 10-15% is a good starting range for most hunting setups.

Common Mistakes to Avoid

  • Including the point or nock in the arrow length measurement, which skews the FOC calculation.
  • Measuring balance point from the tip instead of the nock, leading to incorrect FOC.
  • Using inconsistent units (e.g., mixing inches and centimeters) without conversion.

Last updated: August 13, 2026