FOC Calculator

Arrow Front of Center (FOC) Explained

This FOC Calculator computes the front-of-center percentage of an arrow from its total length and balance point distance from the nock. FOC indicates how much arrow weight sits forward of center, affecting flight stability and penetration.

The FOC Formula

FOC% = 100 × (Balance Point − Arrow Length / 2) / Arrow Length. For a 30 cm arrow with an 18 cm balance point, FOC = 100 × (18 − 15) / 30 = 10%. Positive FOC means weight is concentrated toward the point end.

What Is a Good FOC?

Hunting arrows typically perform well between 10% and 15% FOC. Higher FOC improves stability and penetration but may reduce speed. Target archers sometimes prefer lower FOC for flatter trajectory. The ideal value depends on your bow setup and shooting style.

Frequently Asked Questions

How do I measure the balance point?

Balance the arrow on a narrow edge or pin. Measure from the throat of the nock to that balance point along the shaft centerline.

What does a 10% FOC mean?

Ten percent FOC means the arrow's center of mass sits 10% of the arrow length forward of the geometric center, toward the point.

How can I increase FOC?

Add weight to the front (heavier broadhead or insert) or reduce rear weight with lighter vanes or a lighter nock.

Is higher FOC always better?

Not always. Very high FOC can slow the arrow and affect tuning. Most hunters find 10% to 15% FOC is a practical sweet spot.

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Arrow Front of Center (FOC) Explained

The FOC Formula

What Is a Good FOC?

Frequently Asked Questions

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