Arrow Spine — General Starting Point
A general, non-brand-specific starting point. Manufacturer spine charts (Easton, Gold Tip, etc.) are proprietary and more precise — always confirm before cutting arrows.
How this works
Arrow spine describes how much an arrow shaft flexes under load — a lower deflection number means a stiffer shaft. This calculator starts from your draw weight and adjusts it for the factors that change how stiff a shaft you actually need: a longer arrow flexes more (needing a stiffer shaft), a heavier point flexes the shaft more at the front on release (also needing stiffer), and traditional/recurve setups typically shoot a slightly weaker spine than a compound at the same draw weight.
Why this is only a starting point
Manufacturer spine charts (Easton, Gold Tip, Victory, and others) are built from extensive real-world testing with their specific shaft materials and are meaningfully more precise than any generic formula. Always confirm the exact spine against your arrow manufacturer's own chart before cutting shafts to length — a mis-spined arrow is expensive to fix after the fact.
Frequently asked questions
What happens if my arrow spine is too weak for my setup?
A weak (understiff) arrow can flex excessively off the string, especially from a compound bow's cams, leading to inconsistent flight and sometimes a porpoising or fishtailing arrow in the air.
Is it better to be a little too stiff or a little too weak?
Slightly overstiff is generally the safer, more forgiving direction — manufacturer charts often build in a margin toward stiffer for exactly this reason.
Should I trust this over my arrow manufacturer's own spine chart?
No — this is a deliberately general, non-brand-specific starting point. Manufacturer charts (Easton, Gold Tip, and others) are built from real-world testing with their specific materials and are meaningfully more precise.
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