What does the number of spines means for arrow?

Ask any experienced archer what’s the most critical factor for accurate, safe shooting, and “arrow spine” will likely top their list. Yet for beginners, spine numbers (like 300, 500, or 700) often feel like a confusing code. What do these numbers actually mean? And how do you pick the right spine for your recurve, compound, or traditional bow?

This guide breaks down arrow spine in simple terms: we’ll explain what spine numbers represent, why they matter for performance and safety, and walk you through a step-by-step process to match your bow with the perfect arrow spine. Whether you’re target shooting, bowhunting, or just starting out, understanding spine will transform your consistency and confidence.

What Do Arrow Spine Numbers Mean?

At its core, arrow spine is a measure of an arrow shaft’s stiffness—how much it flexes when force is applied (specifically, when the bowstring pushes it forward upon release) . The spine number directly correlates to this stiffness:

• Lower spine number = Stiffer arrow: A 300-spine arrow is significantly stiffer than a 700-spine arrow. For example, a 400-spine carbon arrow bends just 0.400 inches under standard testing, while a 700-spine arrow bends 0.700 inches .
• Higher spine number = More flexible (weaker) arrow: Flexible arrows are better suited for lower draw weights, as they need to flex enough to absorb and transfer energy efficiently.

Static vs. Dynamic Spine: Key Distinctions

To fully grasp spine, you need to understand two types—static and dynamic—since both impact your arrow’s performance:

1. Static Spine (Measured Stiffness)

Static spine is the industry-standard measurement used to assign those numbers. Manufacturers test it by:

• Supporting the arrow shaft at two points exactly 28 inches apart.
• Hanging a 1.94-lb weight from the center.
• Measuring how far the shaft deflects (bends) in thousandths of an inch .

This static rating is what’s printed on arrow shafts (e.g., “500 spine”), but it’s just a starting point. Real-world shooting depends on dynamic spine.

2. Dynamic Spine (Real-World Flex)

Dynamic spine describes how the arrow flexes when you actually shoot it—and it’s influenced by far more than just the static rating. Factors like your bow’s draw weight, arrow length, point weight, and release style all alter dynamic spine . For example:

• A 500-spine arrow might act “weaker” (more flexible) if you use a 125-grain broadhead instead of a 100-grain field point.
• A longer arrow (30 inches vs. 28 inches) of the same static spine will behave more flexibly in flight.

Dynamic spine is why two archers with the same bow might need slightly different spine ratings—your unique setup and shooting style matter.

Why Arrow Spine Matters (Safety + Performance)

Choosing the wrong spine isn’t just a matter of missed targets—it’s a safety risk. Here’s why it’s non-negotiable:

1. Accuracy & Consistency

• Too weak (overly flexible) spine: The arrow flexes excessively during flight, causing “fishtailing” or wobbling. For right-handed shooters, weak arrows often veer left; left-handed shooters may see arrows drift right . Groups will be wide, and long-distance shots will be unpredictable.
• Too stiff (over-spined) spine: The arrow doesn’t flex enough to clear the bow’s riser or rest properly. It may hit right (right-handed shooters) or left (left-handed) and create harsh vibrations that throw off aim .
• Correct spine: The arrow flexes just enough to absorb the bow’s energy, then recovers quickly to fly straight. This ensures consistent shot placement, even at 50+ yards.

2. Safety

Using an under-spined (too weak) arrow with a high-draw-weight bow is dangerous. The excessive flex can cause the shaft to splinter, crack, or even break mid-flight—sending debris flying or damaging your bow . Over-spined arrows also increase bow vibration, which can wear down components over time.

3. Bow Tuning

The right spine makes tuning your bow (e.g., paper tuning, bare-shaft testing) far easier. When your arrows flex consistently, you can diagnose issues like rest misalignment or fletching contact—instead of blaming “bad form” on a mismatched spine.

Factors That Determine Your Ideal Spine

To select the right spine, you need to know five key details about your setup. Gather these before you start:

1. Bow Type (Compound vs. Recurve vs. Traditional)

Different bow designs transfer energy differently, so spine requirements vary:

• Compound bows: High draw weights (30–80 lbs) and fast arrow speeds demand stiffer spines. The cam system creates a sharp energy spike, so arrows need rigidity to handle the force .
• Recurve bows: Lower draw weights (20–60 lbs) and finger releases (which add side pressure) often require more flexible spines than compounds .
• Traditional longbows: Finger releases and longer draw lengths mean even more flexibility is needed—op for weaker spines than you would for a recurve of the same draw weight .

2. Bow Draw Weight

This is the single biggest factor. Heavier draw weights (e.g., 60+ lbs) need stiffer arrows (lower spine numbers), while lighter draw weights (20–30 lbs) work with more flexible arrows (higher spine numbers) .

3. Arrow Length

Arrow length is measured from the throat of the nock to the end of the insert (not the tip) . Longer arrows flex more than shorter ones, so:

• If you shoot a 30-inch arrow, you’ll need a stiffer spine than a 28-inch arrow of the same static rating .
• A general rule: Add 1 inch to your draw length to get your ideal arrow length (e.g., 27-inch draw length = 28-inch arrow) .

4. Point Weight (Field Tip/Broadhead)

Heavier points (125–150 grains) make arrows flex more (weaker dynamic spine), while lighter points (85–100 grains) reduce flex (stiffer dynamic spine) . For example:

• If you’re using a 150-grain broadhead for hunting, you may need to step down one spine number (stiffer) from what you’d use for a 100-grain field tip .

5. Release Style

• Finger release (common with recurves/longbows): Adds side pressure to the arrow, increasing flex. You’ll need a weaker (more flexible) spine than if you used a release aid .
• Release aid (common with compounds): Pulls the string straight back, reducing side pressure. Opt for a stiffer spine than you would for finger release.

Step-by-Step: How to Choose the Right Arrow Spine

Now that you have your setup details, follow these steps to find your perfect spine:

Step 1: Confirm Your Bow Specs & Setup

Write down:

• Bow type (compound/recurve/longbow)
• Draw weight (lbs, e.g., 45 lbs)
• Draw length (inches, e.g., 28 inches)
• Desired arrow length (draw length + 1 inch = 29 inches)
• Point weight (e.g., 100 grains)
• Release style (finger/release aid)

Step 2: Use an Arrow Spine Chart (Critical Tool!)

Spine charts are the industry standard for matching arrows to bows. Below are simplified charts for common bow types (based on 100-grain points—adjust for heavier/lighter points as needed) :

Compound Bow Spine Chart (Release Aid)

Recurve Bow Spine Chart (Finger Release)

Traditional Longbow Spine Chart (Finger Release)

Note: If using a 125–150 grain point, go one spine number stiffer (e.g., 600 → 500). If using 85-grain points, go one number weaker (e.g., 500 → 600) .

Step 3: Cross-Reference with Manufacturer Charts

Every arrow brand (e.g., Gold Tip, Easton, Black Eagle) has its own spine charts, tailored to their shaft materials (carbon, aluminum, hybrid). For example:

• Gold Tip’s spine selector tool accounts for specific shaft models (e.g., Hunter XT vs. Pierce) .
• Easton’s aluminum arrow charts use a different numbering system (e.g., 1916 = 500 spine equivalent) .

Always check the manufacturer’s chart for your arrow brand—this ensures the most precise match.

Step 4: Test & Tune (Final Adjustment)

Even with a chart, real-world testing is key. Here’s how to fine-tune:

1. Bare-Shot Testing: Shoot one bare shaft (no fletching) and one fletched arrow at 20 yards.
   • If the bare shaft hits left (right-handed): Arrow is too weak → go stiffer spine.
   • If it hits right: Arrow is too stiff → go weaker spine.
2. Paper Tuning: Shoot through a piece of paper at 6–10 yards.
   • Tear to the left: Weak spine.
   • Tear to the right: Stiff spine.
   • Clean hole: Perfect spine!

Step 5: Consult a Pro Shop (Beginner-Friendly)

If you’re unsure, visit a local archery pro shop. Experts can measure your draw length/weight, analyze your release, and test arrows with your bow—saving you time and money on mismatched shafts . Online retailers like Lancaster Archery or 3Rivers Archery also offer free spine selection help over the phone.

Common Arrow Spine Mistakes to Avoid

1. Ignoring point weight: Using a 150-grain broadhead with the same spine as a 100-grain field tip will lead to poor flight .
2. Choosing based on draw weight alone: Forgetting arrow length— a 45-lb bow with a 30-inch arrow needs a stiffer spine than a 45-lb bow with a 28-inch arrow .
3. Overlooking release style: Finger releases need weaker spines than release aids—don’t use compound-specific arrows for a recurve with finger release .
4. Assuming “stiffer = better”: Stiffer arrows aren’t always superior—they can cause riser contact and vibration if mismatched .

FAQ: Arrow Spine Basics

Q: Can I use the same spine for hunting and target shooting?

A: Yes—if you adjust for point weight. For example, use a 500-spine arrow with a 100-grain field tip for target shooting, and the same 500-spine arrow with a 125-grain broadhead for hunting (the heavier point will soften the dynamic spine just enough).

Q: Do carbon arrows have different spine rules than aluminum?

A: The core principles are the same, but carbon arrows are stiffer per weight than aluminum. For example, a 500-spine carbon arrow is lighter and stiffer than a 500-spine aluminum arrow .

Q: What if my draw weight is between two spine ratings?

A: Go with the stiffer spine if you plan to use heavier points or longer arrows. Go weaker if you use lighter points or shorter arrows. Testing will help you decide.

Conclusion

Arrow spine numbers don’t have to be confusing—they’re simply a measure of stiffness, with lower numbers meaning stiffer shafts. The key to choosing the right spine is understanding how your bow’s draw weight, arrow length, point weight, and release style influence dynamic spine.

By following the steps above—gathering your specs, using a spine chart, testing, and tuning—you’ll find arrows that fly straight, hit consistently, and keep you safe. Whether you’re a beginner with a 30-lb recurve or an experienced hunter with a 70-lb compound, the right spine is the foundation of great shooting.

Remember: Archery is a sport of precision, and spine is one of the most precise choices you’ll make. Take the time to get it right, and you’ll see immediate improvements in your groups, confidence, and enjoyment.