Archery term
FOC (Front of Center)
What does FOC (Front of Center) mean?
FOC, or front of center, is an arrow's balance point measured forward of the arrow's midpoint and expressed as a percentage of arrow length. To calculate it, subtract half the arrow length from the distance from the nock throat to its balance point, divide by arrow length, then multiply by 100.
Primary source for this term: Easton Archery: F.O.C. Calculator (Accessed 2026-10-07)
Why it matters
FOC is one way to describe how the arrow's mass is distributed. It changes when you change the point, insert, shaft, or rear components, but a larger FOC is not automatically better. Compare builds for the job and check the shaft maker's minimum arrow-weight guidance before changing components.
What to check
- Measure the finished arrow from the nock throat to its balance point, then use the stated formula.
- Compare point and insert mass as one part of the build.
- Follow the bow or crossbow maker’s minimum finished-arrow mass, not a shaft-only minimum; a higher FOC is not automatically better.
Useful next steps
