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Arrow Tuning Tool

FOC Calculator

Measure the finished arrow from the throat of the nock to the end of the shaft, then enter the balance point from the nock to see front-of-center percentage.

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How This Tool Works

FOC is a balance measurement.

This calculator uses the standard front-of-center formula: balance point minus half the arrow length, divided by arrow length, multiplied by 100. The only data it uses is what you enter on this page.

Measure arrow length from the throat of the nock to the end of the shaft, then measure the finished arrow's balance point from that same nock reference. Broadheads, inserts, collars, wraps, vanes, and lighted nocks all change the result, so measure the finished arrow you actually plan to shoot.

The guidance ranges are general tuning language for compound hunting setups. They are not a replacement for shooting groups, broadhead tuning, or checking whether your arrow spine still matches the build.