It’s crucial to match the arrow’s spine to your equipment for precision. As you construct your arrows, you must also know how you might affect the arrow’s spine. You can see the arrow stretching during the first few yards of flight if you view a video of an arrow exiting a bow in ultra-slow motion. This is because the arrow’s spine, which measures the arrow’s stiffness, causes the in-flight flexing.
Arrow makers provide a spine chart that details the stiffness of their arrows. The greater the number, the weaker the spine is usually. The stiffest spine arrows are 300, 400, 500, and 600. Arrow flexing is affected by all three parameters. Higher draw weights and longer arrows shot by archers with long draw lengths need stronger arrows.
Assume you have a 50-pound compound bow with Gold Tip arrows 27 inches long. If the arrow has a 100-grain point, Gold Tip recommends a 500-spine rating. If you use the same 50-pound bow but lengthen the arrow to 30 inches, the chart recommends a spine of 400.
When bow draw weight increases to 60 lbs., the 27-inch arrow is shot, charts ask for a 400 spine. (Find the Best Budget Red Dot)
Raw arrows shipped measure 33 inches and get firmer as you cut them to meet your draw length. For example, for a 27-inch arrow shot at 60 pounds, Gold Tip recommends the 400 spine over the 340.
When picking arrows, archers frequently mix them up. For example, depending on where your arrow rest is positioned and how much arrow extends in front of the riser while you’re at full draw, archers with a 27-inch draw length may shoot arrows ranging from 26 to 29 inches.
When looking at the spine charts, use the arrow length you want to shoot.
Archers should select arrows based on the manufacturer’s spine recommendations. Getting away from those suggestions can harm accuracy. In addition, archers make mistakes when changing the spine of their arrows to adjust the total weight of their arrows.
In our guide, you can find the right arrows using an arrow spine calculator chart. By the end, you’ll know how to read the arrow spine chart to find the right draw weight and arrow length, weight, and more.
Are 340 Or 400 Arrows Heavier?
Materials in arrows can lead to a weight difference as much as the diameter of the shaft.
Here, you can see the major material and how to select the right spine, to find out what spine arrow do I need?
Carbon Arrow
Carbon arrows dominate the market as they are lighter, faster, and penetrate better because of their smaller diameter and not flexing like aluminum arrows.
Aluminum Arrow
Aluminum arrows are an excellent choice if you don’t care about speed and prefer a heavier arrow. Aluminum arrows are quieter out of the bow and have a more comprehensive spine selection. (Learn How to Build an Archery Target for a Compound Bow)
Aluminum/Carbon Arrow Mix
Aluminum/Carbon arrows combine the best features of carbon and aluminum. The small diameter and thick carbon wall in the middle of these arrows ensure consistent arrow flight, spine, straightness, and improved penetration.
Choosing the Right Arrow Spine
Shooting something resembling a banana would be like shooting an arrow that isn’t spined right.
Mid-flight, the arrow will flex, causing discrepancies downrange. This is the most important consideration when choosing a hunting arrow.
Arrow Spine
The spine is a measure of the stiffness of the arrow, the lower the number, the stiffer the arrow.
Static Spine
The arrow’s static spine is measured when a 1.94-pound weight is hung from the arrow’s center. To compute this, arrows must be 29″ long and supported at two locations 28″ apart.
The arrow’s spine is the number of inches the arrow bends multiplied by 1,000.
For example, once the weight is applied, if your arrow has the number 350, it will bend .350″.
Dynamic Spine
The way an arrow reacts to the stored energy as the bow is shot is known as dynamic spine. This accounts for infinite variables and components of the arrow, including broadhead design, fletching weight, extra arrow wraps, insert weight, and bow speed.
Shortening the arrow, lowering the bow weight, changing the point/insert weight combination, or adding weight to the back of the arrow can all stiffen the dynamic spine of an arrow.
A static spine chart below can help you select the correct spine.
What Do Arrow Sizes Mean?
Some arrow manufacturers have quite complicated charts that adjust for many variables. On the other hand, other arrow producers provide a more simplified chart with an arbitrary number system, such as the example chart here, which just refers to draw weight and arrow length. (Read What Is The Only Arrowhead That May Be Used For Big Game Hunting)
Using the simple chart method, you’ll have to use some common sense, especially if your bow configuration isn’t quite ‘average.’
The simplified chart, for example, works perfectly if you shoot a conventional 310 fps compound bow with normal 100-gram tips and a 75 percent let-off.
If your bow is configured for 60 pounds and you shoot 29-inch arrows, simply follow the dots on the chart and select the 2000 spine size. Easy!
If you shoot a high speed-bow with an IBO Speed of 350 fps? It produces more energy than a typical 60# bow.
Knowing how to accommodate a stiffer spine, such as a 3000 shaft, what about if you up your arrow to a 125-grain tip?
For more in-depth charts, you can check the Black Eagle Arrows website to see what the arrow manufacturers offer, how they deal with arrows shafts, bow type, and how adding weight to arrow shafts can affect a weaker spine.
What Is Spine Deflection?
The advertised spine size of an arrow differs from the actual spine deflection. However, the real arrow spine deflection is a direct technical measurement.
The spine deflection of an arrow is tested by suspending a 1.94 lb. weight in the middle of a 28″ suspended piece of the arrow shaft.
The arrow’s spine deflection results from the 1.94 lb. arrow weight sagging the shaft. For example, a 1.94 lb. weight causes a 28″ arrow’s center to sag 1/2 inch (.500″).
The spine deflection measurement of a limber arrow will be higher. So, it’s handy to know the difference between spine deflection and stiffness.
Bow
| Draw weight lb. | 25" | 26" | 27" | 28" |
|---|---|---|---|---|
| 15-20 | 700 | 700 | 700 | 600 |
| 20-25 | 700 | 700 | 600 | 600 |
| 30-35 | 600 | 600 | 600 | 500 |
| 35-40 | 600 | 600 | 500 | 500 |
| 40-45 | 600 | 500 | 500 | 500 |
| 45-50 | 500 | 500 | 500 | 400 |
| 50-55 | 500 | 500 | 400 | 400 |
| 55-60 | 500 | 400 | 400 | 400 |
| 60-65 | 400 | 400 | 400 | 350 |
| 65-70 | 400 | 400 | 350 | 350 |
| 70-75 | 400 | 350 | 350 | 350 |
| 75-80 | 350 | 350 | 350 | 300 |
| 80-85 | 350 | 350 | 300 | 300 |
| 85-90 | 350 | 300 | 300 | 250 |
| 90-95 | 300 | 300 | 250 | 250 |
| 95-100 | 300 | 250 | 250 | 250 |
What is The Standard Size Arrow?
Before using any size chart, you need to know how arrows are measured.
Aluminum Arrows
Aluminum arrows mark the shaft’s diameter and thickness. In addition, they’ll have a four-digit number.
- Here, the first two numbers are the diameter in 64ths of an inch. If the first two numbers are 16, that shows 16/64 inches.
- The second and third numbers represent the thickness in 1000ths of an inch, respectively. For example, the shaft is 17/1000 inches thick if the second two numbers are 17.
Carbon Arrows
Carbon arrows are measured by their spine deflection or how much they bend. The lower the number, the stiffer the spine.
Most of the scores range from 260 to 500. This technique is also used in aluminum and carbon-fiber combinations. (Read Marine Battery Sizes Chart)
Arrow Length
The distance in inches from where the string sits on the nock to the end is the usual technique of measuring an arrow. The tip is not included in this measurement.
Manufacturers may measure from tip to tip or the arrow’s shaft when providing you with this information. The best approach to determine the length is to take your measurements.
Arrow Size Chart
This size chart is divided into labeled rows and columns, with the matching cell showing which arrow you require.
Your bow weight will be in the rows, and your arrow length will be in the columns.
What Size Arrow for My Bow?
What size you need depends on your bow weight, type, and size.
Bow Weight
The weight of your bow determines the weight of the arrow you need. Archers usually weigh their targets in grains or grains per inch (GPI). The diameter thickness determines GPI and materials used. Heavier bows require heavier arrows and vice versa.
Bow Type
Arrows of assorted sizes are required for various bows. Because recurve bows are lighter than compound bows, smaller arrows are required. Compound bows are capable of handling heavier loads. If they have aggressive cams, they may also require stiffer arrows.
Bow Size
The draw length determines the bow size, which is related to the drawing weight. As a result, the greater your draw weight, the longer your draw length, and the larger your bow.
As the draw weight increases, you should reduce the spine deflection. For each pound of draw weight, you should have at least five grains of weight.
What Size Of Arrow Do I Need?
In archery, arrow size can determine plenty. Therefore, accuracy is one of the critical variable setup factors.
For instance, Heavier bows and higher bow weight need heavier and stiffer arrows, so you need to know which are the best arrows for any specific bow.
Arrow Diameter
The diameter of a hunting arrow is also essential. Should you use a medium-sized arrow or a micro-sized arrow?
Smaller diameter shafts provide better penetration because of reduced surface area and friction and allow the arrow to keep the momentum for longer.
The reduced surface area of a smaller diameter arrow reduces drift on a windy day. In addition, less weight toward the front allows better flight characteristics and long-range accuracy with micro-diameter shafts.
Arrow Straightness
Straightness matters in any arrow. This is significant now because of improved bow efficiency.
It’s tough to say if some individuals can distinguish between one-carbon arrow and another, yet why risk it when west bow-hunting. It will, however, come with a higher price point.
Correct Arrow Weight
All arrow weights are in grains per inch (GPI), whereas lighter weight arrows are preferred for speed.
Lighter arrows fly quicker and straighter, but they are difficult to tune and need a precise form; thus, you may find they fire better using a finger release.
Heavy arrows have more kinetic energy and motion and fly straighter. The additional momentum of a heavier arrow resists wind drift yet needs a higher bow weight.
Arrow Selection Process
Here are the steps when ordering new arrows:
- Pick a target weight that you want to shoot. This is the maximum poundage your bow limbs allow.
- Try to narrow down the arrow selection from manufacturers.
- After choosing an arrow brand, decide on arrow performance. For example, do you need a light and quick arrow for a higher bow weight or a big arrow?
- Determine your draw length, poundage of bow, arrow length, and point weight. Next, choose your arrows based on these preliminary numbers. Then you calibrate your bow and arrows.
- You can use these details in any archery software online, such as “The Archery Program” or “Archers Advantage.”
- Such software can tell you if your arrow is too weak or stiff based on draw weight, length, and point weight.
- To determine the right arrow shaft size, you may need to experiment with length, arrow spine, and bow speed before fine-tune your choice.
