Arrow Spine Explained: How to Match Arrows to Your Bow

If your arrows fishtail or drift to one side no matter how steady your aim feels, the problem is rarely your form — it’s usually your spine. Arrow spine explained in plain terms: it’s how much an arrow flexes when it leaves the string, and matching it to your bow is the fastest, cheapest way to tighten your groups.

What Is Arrow Spine, Actually?

Spine is a measure of how much an arrow bends under load. The moment you release, the string dumps a burst of energy into the back of the arrow. That energy doesn’t push in a perfectly straight line — the nock accelerates faster than the point for a split second, and the shaft flexes to absorb the difference. A correctly spined arrow bends just enough to soak up that wobble, then “recovers” into straight, stable flight a few metres downrange.

Spine is rated by deflection. In the most common system, the number tells you how far the middle of a 28-inch shaft bends when a standard 1.94-pound weight hangs off it. A 500-spine arrow deflects 0.500 inches; a 300-spine arrow deflects only 0.300 inches. Lower numbers mean stiffer shafts — a 300 arrow is stiffer than a 600 arrow.

Why does any of this matter? An arrow that’s too weak (bends too much) or too stiff (barely bends) can’t fly true. Too weak, and the tail whips sideways — the tail wagging the dog. Too stiff, and the arrow leaves the bow at a slight angle it never fully corrects. Either way, your groups open up, and you’ll blame your release for what’s really an equipment mismatch.

How to Match Arrows to Your Bow

Getting the right spine comes down to three numbers and one field test. Here’s the sequence we walk every new archer through at the range — and it applies to both recurve and compound bows.

1. Measure your draw weight at full drawThe bow’s rated weight assumes a 28-inch draw. Your holding weight at full draw is what counts — we measure it with a bow scale.
2. Measure your draw lengthArrow length runs roughly your draw length plus an inch or so. Longer arrows absorb more energy, which effectively changes the spine you need.
3. Read the spine chartEvery arrow maker publishes a chart matching draw weight plus arrow length to a spine number. Treat it as a starting point, not gospel.
4. Field-test your groupsShoot and watch the tail. Consistent left/right drift or fishtailing means you’re off — try the next spine up or down and compare.

Frequently Asked Questions

What happens if my arrow spine is too weak?

The arrow bends too much and the tail can kick out sideways — often landing left for a right-handed shooter. Groups stay loose no matter how clean your release is.

What happens if my arrow spine is too stiff?

A stiff arrow doesn’t flex enough to clear the bow cleanly, so it leaves the string at a slight angle. You’ll see consistent grouping off to one side that no amount of aiming fixes.

Does increasing draw weight change the arrow spine I need?

Yes. More draw weight dumps more energy into the arrow, so a stiffer (lower-number) spine is usually required as you work up in poundage. Re-check every time you jump up in weight.

Do I need different arrows for recurve and compound bows?

Often, yes. Compounds are generally more forgiving of spine, but they also shoot faster and can demand stiffer arrows. Match arrows to each bow you own rather than assuming one set fits both.

About the Author
Coach Taylor is a Precision Sports Instructor at OnPoint Archery in Scarborough, Toronto, with seven years of coaching experience across recurve, compound, and airgun disciplines. Taylor specializes in equipment setup and beginner tuning, and believes the right arrow is half of accuracy — a lesson taught to every first-time archer who walks onto the range floor.