Foc Calculator
Calculate the Front of Center (FOC) percentage for arrows. FOC helps optimize arrow flight and penetration for archery.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the FOC Calculator
This tool calculates the Front of Center (FOC) percentage for an arrow, which indicates how much weight is forward of the arrow’s center. A higher FOC (typically 7–15%) improves stability and penetration.
- Step 1: Enter the Arrow Length in inches (e.g., 30). Use positive numbers only.
- Step 2: Enter the Balance Point from Nock in inches (e.g., 18). This is the distance from the nock end to where the arrow balances.
- Step 3: Click Calculate FOC. The result appears as a percentage.
Formula: ((Balance Point − Arrow Length ÷ 2) ÷ Arrow Length) × 100
Note: All measurements must be in inches. If you have metric values, convert to inches first (1 inch = 25.4 mm).
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Frequently Asked Questions
FOC stands for Front of Center, a percentage that indicates the balance point of an arrow relative to its length. It affects arrow flight and penetration.
FOC = ((Balance Point from Nock - Arrow Length/2) / Arrow Length) × 100.
For target archery, 10-15% is common. For hunting, 12-20% is often preferred for better penetration.
