What is Arrow FOC?
Front of Center (FOC) is a measure of how far forward an arrow’s balance point sits compared to its physical midpoint. It’s expressed as a percentage of the arrow’s total length and is a key factor in arrow flight stability, penetration, and how forgiving the arrow is of minor form errors.
How FOC is calculated
To measure FOC, balance the fully assembled arrow (with point/broadhead, insert, fletching, and nock installed) on a level edge and note the distance from the nock end to that balance point (C). FOC is then calculated as ((C – Length/2) / Length) x 100, where Length is the total arrow length. A higher balance point toward the front (a heavier point relative to the shaft and fletching) produces a higher, positive FOC.
Most hunting arrows perform well with FOC in the 10-15% range, while target and recreational arrows are often built closer to 7-12%. Very high FOC (15%+) can improve penetration and stability in wind but may reduce top-end speed slightly; very low or negative FOC can make an arrow less stable in flight.
This calculator is for general archery reference and tuning purposes; always follow your bow and arrow manufacturer’s guidance and local safety practices.