Arrow FOC (Front of Center) Calculator
Calculate the front-of-center (FOC) percentage of your arrow using arrow length and balance point. Free online FOC calculator for archers, hunters, and target shooters.
About This Calculator
The Arrow FOC (Front of Center) Calculator helps archers, hunters, and target shooters determine the balance point of their arrows. FOC is a critical metric that measures how much of an arrow's weight is concentrated toward the front, directly affecting flight stability, accuracy, and penetration performance.
This calculator uses the standard FOC formula: FOC% = ((B − A/2) / A) × 100, where A is the full arrow length measured from the throat of the nock to the end of the arrow shaft, and B is the distance from the throat of the nock to the arrow's balance point. The balance point is found by carefully balancing the arrow on a thin edge such as a knife blade or purpose-built FOC tool.
A FOC percentage between 10% and 15% is generally recommended for hunting setups with broadheads, as the forward weight concentration improves penetration and stability. Target and 3D archers often prefer 7% to 12% FOC for a balance of accuracy and trajectory. Many professional archers tune their arrow FOC by adjusting point weight, shaft length, or component choices to match their specific shooting style and bow setup.
Regional Notes
Arrow FOC measurement is universal and used by archers worldwide. Length measurements can be in inches, centimeters, or millimeters. In the US and UK, inches are most common for arrow lengths. In India and other metric countries, centimeters are typically used. The FOC formula works identically regardless of the unit system as long as A and B are in the same units.
Frequently Asked Questions
What is arrow FOC?
Arrow FOC (Front of Center) is a measure of an arrow's balance and overall performance. It indicates how much of the arrow's weight is concentrated toward the front of the arrow. A higher FOC means more weight forward, which increases stability in flight and improves penetration.
How do you calculate arrow FOC?
Arrow FOC is calculated using the formula: FOC% = ((B - A/2) / A) × 100, where A is the full arrow length from the throat of the nock to the end of the shaft, and B is the distance from the throat of the nock to the balance point. First measure the full arrow length, then find the balance point and measure its distance from the nock throat.
What is a good FOC for an arrow?
The ideal FOC depends on your shooting style. For hunting arrows, a FOC of 10% to 15% is recommended for better penetration with broadheads. For target shooting, a FOC of 7% to 12% is common. For long-distance shooting, a lower FOC around 7% to 10% may be preferred. Ultimately, the best FOC depends on your specific setup and shooting style.
What are the benefits of a higher FOC?
A higher FOC helps the arrow fly more accurately and penetrate more deeply into the target, allowing for more consistent and precise shooting. Additionally, a higher FOC can result in increased velocity, enabling the arrow to reach greater distances while maintaining accuracy.
How can I increase the FOC of my arrow?
You can increase FOC by adding weight to the front of the arrow using heavier broadheads, brass inserts, or weighted points. Alternatively, reduce the weight of the arrow shaft by using lighter materials or reducing the arrow's diameter. Using heavier vanes or adding wrap material near the nock will decrease FOC.
What is the difference between high and low FOC?
A high FOC (above 10%) concentrates more weight forward, providing better stability, deeper penetration, and improved accuracy in windy conditions. A low FOC (below 7%) shifts weight toward the rear, which can help with longer-distance trajectory but may result in less stable flight and reduced penetration.
Does arrow length affect FOC?
Yes, arrow length directly affects FOC. Longer arrows have a greater midpoint distance, which typically results in a lower FOC percentage for the same balance point position. Shortening your arrow will increase FOC assuming the balance point stays in the same relative position.
What FOC percentage is best for hunting vs target shooting?
For hunting, a FOC of 10% to 15% is ideal as it provides better broadhead penetration and more stable flight through brush and wind. For target shooting and 3D archery, a FOC of 7% to 12% works well. For long-range target shooting, some archers prefer a slightly lower FOC around 8% to 10% for flatter trajectories.