How to Calculate Arrow Weight and Why (2024)

FAQs

How to Calculate Arrow Weight and Why? ›

The mass of modern arrows are described in grains per inch (gpi). Most arrows will have the gpi marked right on the shaft. To calculate total arrow mass, take the length of your arrow in inches and multiply that by the gpi weight of the arrow, and then add everything else on the arrow: vanes, nock, insert, arrow head.

Grains per inch is the industry standard for measuring arrow weights. An arrow's GPI determines the arrow shaft's weight. It includes the arrow's length, diameter, wall thickness and shaft material. The GPI number does not include the nock, insert, point or fletchings.

A general rule of thumb is to choose a point weight that is between 5 and 10 grains per pound of draw weight. For example, if a bow has a draw weight of 50 pounds, a point weight of 250-500 grains would be appropriate.

As draw weight increases, so should arrow rigidity (spine). Also, we strongly recommend that you use an arrow with at least 5 grains of weight per pound or draw weight (if you are shooting a 60 lb. bow, you should use and arrow of not less than 300 grains). This includes your field point or broadhead.

Dr. Ed Ashby recommends a much heavier setup for maximum performance, starting at 650 grains for deer-sized animals. For my personal setup, I found myself somewhere in the middle of those two trains of thought. I shoot 570 grain arrows from my 65-lb Mathews VXR with a 30-inch draw length.

To calculate the weight, use the following general formula: W = mg. Here, “W” is the weight of the object, “m” is the mass of the object, and “g” is the acceleration due to gravity. On Earth, the value of g is 9.8 m / s².

The importance of mass weight in archery cannot be overstated. It is a critical factor that affects the stability and accuracy of the bow and can greatly impact the archer's ability to shoot accurately.

The Standard Arrow is a mighty beast. With a shaft thickness of 3/8”, a length of no less than 31 ½ inches from nock to forged head; a type 10, 16 or similar. With 6 inch long fletchings a minimum of ¾” high, the overall weight of the arrow is 800 grains.

Arrow weight: Again, the rule of thumb is that for every 5 grains of added arrow weight, you will drop raw speed by 1-2 fps. Bowstring weight: Adding weight to a bowstring (peep sight, string silencers, string loop) will affect raw speed, but not by much.

Begin by determining the intended function of the point. If you're a bowhunter, select a broadhead or specialty point for specific animals you're after. Practice with field points that match the weight of your broadhead. If you're a target archer, field points will work for you almost every time.

What poundage is a 400 spine arrow good for? ›

That's why Gold Tip recommends the 400 spine for a 27-inch arrow shot at 60 pounds, as compared to the 340 at 30 inches. Understand that the manufacturers' charts refer to arrow length, not draw length.

An arrow that is flying “nock left” indicates a weak spine. In this situation, you can remove some tip weight or shorten the length of the arrow.

The 3555 roughly fit a 35-55# bow, a 5575 fit a 55-75# bow, and a 7595 fit a 75-95# bow.

Not only will a heavier arrow hit harder, but it will retain its energy better through the target. This is a big benefit that will lead to more pass-throughs on bigger animals. Heavy arrows will also quiet your bow down. This is due to the heavier arrow simply absorbing more energy on the shot.

For our purposes, a lightweight arrow will be one that has a finished weight of between 5 and 6 ½ grains per pound of your bow's maximum draw force. For example, a lightweight arrow for a 70-pound bow would have a finished weight (including broadhead) between 350 and 455 grains.

The numbers refer to the spine of the arrow. The different spines refer to the stiffness, a 400 spine arrow is generally for bows 40-60 lbs. 350 spine is for bows roughly 55 - 75 lbs, and a 500 spine arrow is for bows roughly 30 - 50 lbs.

The difference is in “spine" or the bendiness of the arrow. A 340 spine arrow is stiffer (more resistant to bending) than a 400 spine arrow. When arrow tuning, for arrows of the same length, 340 arrows may tend to pull left (an indicator of Too Stiff) while 400 arrows may tend to pull right (an indicator of Too Weak).

Grab the bow firmly with one hand on either side of the handle. Then pull it down with firm pressure to measure its weight. Stop when the scale stops increasing, which indicates that you've hit the max draw weight.

The weight of the arrow is determined by how heavy it is in terms of grains per inch (GPI) and then how long the shaft is. Take that and add in all of your accessories like the insert, broadhead/field tip, vanes, arrow wrap, nock, etc to get the total weight.