🎯 Arrow Spine Calculator
Enter your draw weight, arrow length and point weight to get a recommended carbon arrow spine (deflection) range.
How to use this calculator
- Enter your bow’s peak draw weight in pounds.
- Enter your cut arrow length from nock groove to shaft end.
- Enter your field point or broadhead weight in grains.
- Read the recommended spine — lower numbers are stiffer.
Frequently Asked Questions
What does arrow spine actually mean?
Spine is how much a shaft flexes: a 340 spine deflects 0.340 inches under a standard load. Lower spine numbers are stiffer arrows for heavier draw weights.
What happens if my arrows are under-spined?
They flex too much, fly erratically and group poorly — and with broadheads the problem multiplies. Over-spined (too stiff) is more forgiving than under-spined.
Does point weight change spine requirements?
Yes. Heavier points make the arrow act weaker (more flex), so adding 25 grains up front typically requires one step stiffer spine.