FOC Calculator — Arrow Front of Center Balance
Enter your arrow's total length and the distance from the nock end to its balance point to calculate the Front of Center (FOC) percentage — the key number for arrow flight stability, accuracy, and penetration, whether you shoot target, field, or hunting archery.
Unidade
Optimal — versatile target / field archery
- 1
Arrow midpoint
73 ÷ 2 = 36,5 - 2
Balance ahead of midpoint
43 − 36,5 = 6,5 - 3
Front of Center (FOC)
(6,5 ÷ 73) × 100 = 8,9
Como esta calculadora funciona?
FOC (%) = ((balance point from nock − arrow length/2) / arrow length) × 100. Target archery optimal range is 7–12 %; hunting with broadheads 10–19 %. Measure the balance point by balancing the arrow on a fingertip and measuring from the nock groove. Higher FOC = more front weight = better stability but reduced forgiveness.
Fórmula
How this is calculated
Front of Center (FOC) expresses how far forward of the arrow's exact geometric midpoint its balance point lies, as a percentage of total arrow length. A balance point exactly at the midpoint gives 0 % FOC; an arrow whose balance point is 5 cm ahead of the midpoint on a 73 cm arrow has an FOC of (5/73) × 100 ≈ 6.8 %.
Why does FOC matter? An arrow in flight is a projectile that must remain nose-forward. Too little front-weight means the shaft can plane or oscillate erratically; too much front-weight can over-damp the nock-end oscillation and cause poor clearance from the bow. The target-archery sweet spot is broadly 7–12 %, which balances flight stability with low aerodynamic drag. Hunters using fixed broadheads typically prefer 10–19 % because broadheads create substantial drag at the front, and higher FOC counteracts this, improving penetration and consistency at moderate hunting distances.
To find the balance point, lay the arrow across a fingertip or pencil and slide it until the shaft hangs level. Measure from the nock groove (not the tip of the nock pin) to that balance point. Adjusting FOC in practice means moving weight — adding a heavier point or insert reduces FOC distance from nock and increases it from tip; adding a heavier nock or wrap moves weight rearward and lowers FOC.
Perguntas frequentes
For indoor target or Olympic recurve shooting, 7–12 % FOC gives the best combination of stability and consistent grouping. For hunting with broadheads or long-range field archery, 10–19 % provides better flight stability. Compound target archers often shoot in the 10–15 % range.
To increase FOC: use a heavier field point or broadhead, add an insert weight, or use a lighter nock/vane combination. To decrease FOC: switch to a lighter point, add rear weight (heavier nock or vane), or use a shorter point. Each component change shifts the balance point by a small but measurable amount.
Yes, though ideal values differ slightly by discipline. Recurve archers often find 10–12 % ideal for long-distance consistency; compound target archers commonly use 10–15 %; 3D and hunting setups with broadheads benefit from 12–19 % or even higher when extreme penetration matters more than flat trajectory.
Também conhecido como
TG we-Calculate Editorial Team. (2026). FOC Calculator — Arrow Front of Center Balance [Online calculator]. TG we-Calculate. https://we-calculate.com/pt/calculator/foc-calculator
TG we-Calculate Editorial Team. "FOC Calculator — Arrow Front of Center Balance." TG we-Calculate. 2026. https://we-calculate.com/pt/calculator/foc-calculator.
TG we-Calculate Editorial Team, "FOC Calculator — Arrow Front of Center Balance," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/pt/calculator/foc-calculator
@misc{wecalculate_foc_calculator, title = {FOC Calculator — Arrow Front of Center Balance}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/pt/calculator/foc-calculator}}, year = {2026}, note = {TG we-Calculate} }
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