Arrow Efficiency Calculator

Arrow Efficiency Calculator

Use the arrow efficiency calculator to estimate the most efficient arrow for your specific bow set up.

Arrow Efficiency Calculator – Instructions

  1. Select Preferred Arrow Efficiency
    • Max Speed: IBO arrow (5 grains/per pound of draw weight).
    • Max Efficiency: arrow ~10-15% over IBO (5.5 grains/per pound of draw weight).
    • Max Energy: arrow ~20% over IBO (6 grains/per pound of draw weight).
  2. Chronograph Arrow Speed
    • Shoot three arrows and use the average of the three shots.
  3. Enter Data Below for Results
    • Enter speed and arrow weight data into the calculator.
  4. View Results*
    • Dark Blue: Optimal arrow weight.
    • Light Blue: Range of efficient arrow weights.
    • Red: Highlights specific speeds in fps and MAX energy (KE and M).


*All data are approximate.

Use the Arrow Efficiency Calculator to find the optimal arrow for your bowhunting setup.

Arrow Efficiency Calculator

The Importance of Arrow Efficiency | Chasing 300 FPS for the Little Guy

The bow market is constantly changing, and lately bow manufacturers have designed bows specifically for women and bowhunters with shorter draw-lengths. With that in mind, it is inevitable—in my mind anyway—that speed will become a more prominent factor in bow purchases within these groups in the near future. If nothing else, it will at least be easier for individuals to know what the possibilities are.

Technically speaking, here are three arguments for chasing speed.

  1. Increased Energy Efficiency: If you can push an IBO-weighted arrow at 300 fps, then you will be able to shoot a heavier arrow at a faster speed as well, albeit under the magical 300 fps mark. Why does that matter? Kinetic energy, and more specifically, momentum, of a propelled arrow provide the inertia downrange to make an ethical harvest. Bowhunters should strive to shoot an arrow that optimizes arrow speed and weight to maximize energy.
  2. Flat Trajectory: Optimizing the path that the arrow travels from release to impact can greatly increase success. There are at least three scenarios when having a flatter trajectory is a boon.
    1. Long-range: As a Western Coues deer hunter—where spot-and-stalk is the primary method used to hunt these tiny deer in open country—I know a 60-yard shot is a good one. Furthermore, on numerous occasions, I’ve ranged a Coues buck at one yardage, but the animal then moved a few yards prior to me being able to take the shot. A faster arrow with a flatter trajectory will help to cut out some of guesswork associated with long shots, especially at unknown distances.
    2. Short-range: although we might be talking about milli-seconds, one thing is true: sound travels faster than an arrow, even if, propelled at 300 fps or more. At a distance of 20 yards, arrow ducking may not be as much of a factor, but if you are shooting at deer-sized game at 50 yards and beyond, a faster arrow will make it more difficult for that buck of a lifetime to duck your arrow.
    3. Unmarked distances: I shoot an HHA Sports single-pin sight marked in one-yard increments, but I am sure I am in the minority. I’m sure the majority of bowhunters shoot a multiple-pinned sight with pins more likely in 10-yard increments. So, what do you do when your shot presents at a distance in between pin settings? A faster arrow allows the shooter to use the closest marked-distance pin, perhaps held just slightly low or high.

PRECAUTIONS

At extreme speeds, pay close attention to arrow spine. As shot, the 480 spine arrow is matched correctly for the Prodigy, which has an extremely hard cam. However, increasing the draw weight just one pound could mean having to make a switch to a heavier-spined arrow. The effect would be a heavier arrow; thus, a slower speed. Another option to increase spine would be to cut the arrow shorter. With the QAD Ultra drop-away or similar rest, a two-inch shorter arrow than the one tested could be used. In theory, a shorter, heavier-spined arrow with the same target weight of approximately five grains per inch, with a few pounds more draw weight would still shoot 300 fps.

The front of the arrow on this arrow setup has a couple disadvantages. With a 75-grain broadhead, front of center (FOC) on the arrow as tested was right at the suggested 10 percent minimum, which could cause  broadhead flight  to be problematic at the tested speed. The Muzzy MX-3 flew true and paper-tuned fine; however, another broadhead may not, even at the same weight.

The kinetic energy of this arrow is approximately 58, which fits into the standards used by many for small- and even medium-sized game, but the momentum of the arrow was at the low end, just 0.38. In my opinion, this arrow would be fine for hunting Western sub-species of White-tailed deer, like the Coues deer and similar-sized big game, but would not be recommended for a bruiser of a Midwestern whitetail. Additionally, it would make a great 3-D arrow.

CONCLUSION

In my opinion, you should never target a specific arrow speed when setting up an existing or new bow. Rather, it is best to identify a correctly spined arrow that provides enough potential energy and momentum (measured in KE and M) to match both the game you will be hunting and your shot preference. Moreover, if you are willing to do a little extra work, there is no reason why you cannot set up a bow to shoot two or three different arrows, each with a specific task in mind.

Use the Arrow Efficiency Calculator to find the optimal arrow for your bowhunting setup.