🏹 Arrow Spine Calculator
Get a recommended arrow spine from your draw weight, arrow length, and point weight — with the usable stiffer/weaker range — as a tuning starting point to confirm on the bow.
🏹 Recommended arrow spine
Spine is an arrow's stiffness, published as a deflection number — a lower number is stiffer. We convert your setup to an "effective draw weight" (referenced to a 28" arrow with a 100gr point: +5 lb per inch longer, +3 lb per 25gr of extra point) and read a carbon-arrow spine band from it. It's a starting point — bow type and tune matter, and compounds generally want a slightly stiffer spine than the same-weight recurve. Always bare-shaft or paper tune to confirm.
Why spine makes or breaks your groups
An arrow bends as it leaves the bow — the "archer's paradox" — and flexes around the riser before settling into flight. If the shaft is too stiff or too weak for your setup, that flex doesn't clear cleanly and your arrows scatter no matter how good your form is. Spine is the single most important arrow spec to get right.
This tool converts your draw weight, arrow length, and point weight into an effective draw weight, then reads a carbon spine band (300–800) from a published-style chart. Use it to shortlist shafts, then bare-shaft or paper tune to lock it in.
❓ Frequently Asked Questions
What is arrow spine?
Spine is an arrow's stiffness, published as a deflection number — the sag of a supported shaft under a standard weight, measured in thousandths of an inch. A lower number means a stiffer arrow. Matching spine to your bow keeps the arrow flying straight off the shelf or rest.
How do draw weight, arrow length, and point weight affect spine?
Higher draw weight needs a stiffer (lower-number) spine. Longer arrows flex more, so they behave weaker and also need a stiffer spine. A heavier point makes the arrow act weaker dynamically, again calling for a stiffer spine. This calculator folds all three into an effective draw weight and reads a spine band from it.
Does bow type change the spine I need?
Yes. The chart is a carbon-arrow starting point referenced to a 28-inch arrow with a 100-grain point. Compound bows — with hard cams and higher speeds — generally want a slightly stiffer spine than a recurve of the same draw weight, and a recurve's centre-cut and string also matter.
Is a single spine number enough?
Treat the recommendation as a range, not a single answer. The usable range shown covers most setups, but rest type, string material, and your release all shift the ideal. Always confirm by bare-shaft or paper tuning before buying a full dozen.
Lower or higher spine number for a stiffer arrow?
Lower. A 340-spine shaft is stiffer than a 500-spine shaft. As draw weight, arrow length, or point weight go up, you move to a lower spine number.