What does this calculator estimate?

It calculates arrow front-of-center percentage using FOC = ((balance point − half the arrow length) ÷ arrow length) × 100.

Can I change the assumptions?

Yes. Enter values that match your situation and review the displayed assumptions and limitations before using the result.

Is the result guaranteed?

No. The result is an estimate and should be independently verified before any medical, financial, travel, sizing, fitness, or purchasing decision.

FOC Calculator

Calculate an arrow’s front-of-center balance percentage from finished arrow length and balance-point distance measured from the nock throat. Review the assumptions below and continue with the related guides and calculators linked on this page.

Arrow lengthBalance point from nock throat

Fill in the required fields to see your result.

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Use the primary result together with the supporting outputs. Related Calciro resources: [Arrow Speed Calculator](/arrow-speed-calculator), [Kinetic Energy Calculator](/kinetic-energy-calculator), [Momentum Calculator](/momentum-calculator), [How Kinetic Energy Is Calculated](/guides/how-to-use-kinetic-energy-calculator).

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How to Use This Calculator

Enter the requested values using the units shown. Keep all values consistent and review every assumption before interpreting the result.

Formula & Methodology

The calculator applies the displayed formulas directly to the entered values. Supporting outputs expose intermediate calculations rather than hiding them.

Worked example

A 29-inch arrow balancing 17 inches from the nock throat has FOC of about 8.62%.

Measurement conventions differ. Use a completely assembled arrow and the same nock-throat and shaft-end reference points required by your equipment guidance.

Tuning estimate only. Confirm arrow spine, component compatibility and manufacturer guidance before shooting.

Related Guides

How to Calculate Arrow FOC (Front of Center) Balance
Understand how Arrow Front of Center (FOC) balance affects arrow flight, how to calculate your FOC percentage, and what percentage range gives best accuracy for hunting or target archery.

Frequently Asked Questions

What does this calculator estimate?: It calculates arrow front-of-center percentage using FOC = ((balance point − half the arrow length) ÷ arrow length) × 100.
Can I change the assumptions?: Yes. Enter values that match your situation and review the displayed assumptions and limitations before using the result.
Is the result guaranteed?: No. The result is an estimate and should be independently verified before any medical, financial, travel, sizing, fitness, or purchasing decision.

Last updated 7/22/2026