Home Arrow Spine Calculator
Arrow Spine Calculator
Find a starting arrow spine range for your compound bow, recurve, or longbow from actual draw weight, cut shaft length, point weight, and compound setup adjustments. Cross-check the result with the current Easton, Gold Tip, Victory, or other shaft-maker selector before buying. No sign-ups. Instant results.
Last reviewed October 4, 2026 against Easton's current Hunting Arrow Size Selection chart.
Quick navigation: Calculator · Spine Charts · What is Spine? · Brand Calculators · FAQs
Shop arrows in your recommended spine
Once you have your spine number, these are the best places to find matched shafts:
- Optics Planet — recurve, traditional, and carbon shafts by spine
- Carbon arrows on Amazon — Easton, Gold Tip, Carbon Express, Victory
- All arrow types on Amazon — aluminum, carbon, and hybrid shafts
💡 Tip: Always test arrows before buying in bulk. Borrow or buy a few shafts to verify they fly well from your bow.
Example calculation
Let's find a starting spine range for a typical recurve bow setup:
| Measurement | Value |
|---|---|
| Bow type | Recurve bow |
| Draw weight | 45 pounds |
| Arrow length | 29 inches |
| Point weight | 125 grains |
| Starting spine range | 400-350 spine |
Easton's chart uses a 100-grain point as its baseline and adds 3 lb of effective bow weight for each 25 grains above that reference. A 125-grain point therefore moves this 45 lb recurve setup to a 48 lb chart weight; at a 29" cut shaft length, the published starting range is 400-350 spine. Use that range to narrow current shaft options, then confirm the exact model with the manufacturer and tune the finished arrow before ordering a full set.
🎯 Know your spine? Complete your arrow setup:
Reference: Arrow Spine Chart — full draw weight lookup tables
for recurve, compound, and traditional bows.
Next: Arrow Weight Calculator — total arrow weight in
grains.
Then: FOC Calculator — optimise front of center balance.
Then: Kinetic Energy Calculator — verify hunting
power.
Tune: How to Tie a D Loop — install and size your D loop
before paper tuning.
Shop: Archery Supplies — carbon arrows, aluminum shafts, and
components.
Understanding arrow spine
What is arrow spine?
Arrow spine measures how much an arrow shaft bends under a standardized load. In the common carbon-shaft static-spine test, a 29-inch shaft is supported at two points 28 inches apart and an 880-gram (1.94 lb) weight is suspended from the center. The deflection in thousandths of an inch becomes the spine rating.
For example, a 500 spine arrow deflects 0.500 inches (half an inch). Lower numbers mean stiffer arrows (300 is stiffer than 500). Higher numbers mean weaker, more flexible arrows (600 is weaker than 500).
Why arrow spine matters
Every arrow flexes as the bow transfers energy into the shaft. With finger-release bows, that lateral flex is closely associated with archer's paradox and clearance around the bow; center-shot compound setups with mechanical releases behave differently. In every case, the finished shaft still has to react consistently to the specific bow, release, length, and front-end weight.
A suitable spine makes tuning and repeatable flight easier. A shaft that behaves too weak or too stiff for the setup can make tuning difficult or widen groups, but the exact symptom depends on bow type, release method, center-shot geometry, and tune.
Factors that affect required spine
- Draw weight: Higher draw weight = stiffer spine needed (lower spine number)
- Arrow length: Longer arrows behave dynamically weaker, which can require a stiffer (lower-numbered) shaft
- Point weight: Heavier front weight makes the shaft behave dynamically weaker, which can require a stiffer (lower-numbered) shaft
- Bow type: Compounds and recurves require different spines due to how they release energy
- Arrow material: Carbon, aluminum, and wood all have different stiffness characteristics
How to choose the right arrow spine
📏 Measure accurately
Arrow length is measured from the nock throat (where string sits) to the end of the shaft. Don't guess - measure your actual draw length or current arrows.
⚖️ Know your draw weight
Use the actual draw weight at YOUR draw length, not the bow's marked weight. Compound shooters should use peak weight, not holding weight.
🎯 Consider your point weight
Heavier points (broadheads) make arrows act weaker. If you'll hunt with 125-grain broadheads, factor that into your spine selection.
🔍 Test before buying
Buy a few sample arrows in the recommended spine range. Shoot them and see which groups best before ordering a full dozen.
Need a quick reference without the calculator? See the arrow spine chart for draw weight ranges at a glance. Shop carbon arrows on Amazon or browse all arrow types to find shafts in your recommended spine.
Common arrow spine ratings by bow type
Carbon-style spine numbers such as 300, 340, 400, 500, and 600 describe static shaft deflection: lower numbers are stiffer. The correct number cannot be chosen from draw weight alone.
Recurve
Use actual draw weight at your draw length plus finished shaft length and point/component weight.
Compound
Also account for bow speed and release method. Easton's hunting chart explicitly changes effective bow weight for faster compounds.
Longbow / traditional
Use the traditional column or the shaft maker's traditional selector; center-shot geometry and release style can shift tune.
Aluminum
Four-digit aluminum sizes are not interchangeable with a carbon-style spine label. Use the manufacturer's aluminum selection chart.
For a quick visual reference, see our Arrow Spine Chart. For the final purchase, verify the exact shaft model with its manufacturer's current selector.
Easton, Gold Tip & Victory spine selectors
This calculator is not a universal AMO spine formula. Its starting range is based on Easton's published Hunting Arrow Size Selection chart (301055-A), including Easton's point-weight and compound-speed adjustments. Other manufacturers use their own model-specific grouping and component assumptions.
Use the result here to narrow the range, then confirm the exact shaft with the manufacturer you plan to buy.
Easton
Gold Tip
Open Gold Tip's spine selector, which includes total front-component weight guidance.
Victory
Open Victory's arrow guide, which includes bow speed and component inputs.
Once the model-specific result is confirmed, shop shafts in that spine range.
Arrow spine quick reference guide
Understanding spine numbers
| Spine Number | Stiffness | Common Use |
|---|---|---|
| 200-300 | Very stiff | Heavy compound bows (70+ lbs) |
| 300-400 | Stiff | Compounds 55-70 lbs, hunting |
| 400-500 | Medium | Compounds 45-60 lbs, recurves 40-50 lbs |
| 500-600 | Medium-soft | Recurves 35-45 lbs, lighter compounds |
| 600-800 | Soft | Recurves 25-35 lbs, youth bows |
| 800-1000 | Very soft | Youth bows, very light draw weights |
How brand labels differ
Carbon and carbon/aluminum families are sold in model-specific spine sizes, so use the current selector for the exact shaft family rather than assuming every brand offers the same printed numbers. Easton, Gold Tip, and Victory all publish current selection tools linked above.
All-aluminum arrow sizes:
- Easton-style all-aluminum shafts commonly use four-digit size codes such as 1816, 2014, or 2213.
- The first two digits describe approximate outside diameter in 64ths of an inch.
- The last two digits describe wall thickness in thousandths of an inch.
- Carbon/aluminum shafts such as X10 and A/C/E use different model-specific sizing; do not treat them as four-digit aluminum codes.
💡 Always check manufacturer spine charts for your specific arrow model. Spine ratings can vary slightly between brands.
Note: the table above groups draw weights broadly for quick reference. For precise spine by exact draw weight and arrow length, use the detailed recurve and compound tables above, or the calculator at the top of this page.
Arrow spine calculator FAQs
What is arrow spine and why does it matter?
Arrow spine describes shaft stiffness. The shaft flexes when energy is transferred from the bow, and the correct static spine range helps the finished arrow tune and recover consistently for the specific bow setup.
What chart does this calculator use?
The starting ranges are based on Easton's Hunting Arrow Size Selection chart 301055-A. The calculator applies Easton's point-weight adjustment and, for compound bows, the selected speed-rating and release-type adjustment. Final shaft choice should still be checked with the manufacturer of the arrow you intend to buy.
Why can Gold Tip or Victory give me a different result?
Manufacturer selectors use their own shaft families and component assumptions. Gold Tip explicitly includes total front-component weight, while Victory includes bow speed and component inputs. A difference does not mean one tool is universally correct for every shaft; use the selector for the exact model you plan to shoot.
How do I measure arrow length for this calculator?
For the Easton hunting chart used here, measure cut shaft length from the throat of the nock to the end of the shaft, excluding the point and insert. Other manufacturers may define their selector input differently, so follow the wording on the final brand-specific tool.
What is the difference between static and dynamic spine?
Static spine is the shaft's measured deflection under a standardized test. Dynamic spine describes how that finished arrow behaves when shot from a specific bow. Shaft length, front weight, bow speed, release style, and tuning can change dynamic behavior without changing the static spine label printed on the shaft.
Does a heavier point mean I need a weaker spine number?
No. Adding front weight makes the arrow behave dynamically weaker, which can require a stiffer shaft — a lower carbon-style spine number. Easton's hunting chart handles this by adding effective bow weight when the point is heavier than its 100-grain reference.
Can cutting an arrow change its labeled spine?
Cutting a shaft shorter makes it behave dynamically stiffer, but the labeled static spine does not change. A 400-spine shaft remains a 400-spine shaft after cutting. Tune in small increments and stay within the manufacturer's safe length guidance.