Backcountry Bowhunting - Archery Tools

Approximate Arrow Speed

You can use the following to work backwards off listed IBO specs, this will put you pretty close to chrono:

IBO Specs - 30" draw/70lb draw weight and a 350gr arrow.

For every inch of draw length you go down you will lose 10 FPS

For every 5# draw weight you go down you will lose 10 FPS

For every 3 grains of weight your arrow is over IBO ( 5 grains per pound) you will lose 1 FPS

For every 3 grains of weight you add to your string you will lose 1 FPS.

Kinetic Energy

To calculate your arrows KE (kinetic energy) you'll need 2 measurements: your arrow weight and arrow speed. Most archery pro shops have both, a scale and chronograph, available.

How much KE (kinetic energy) do you really need? There are many schools of thought on just how much KE is required for any given animal size. Some argue, after they've picked the kinetic weight, that decreasing arrow weight (which increases speed - thus increasing kinetic energy) is the way to go. Many have tested this approach and found that down-range energy is drastically reduced due to the light arrow weight. In other words, KE starts out well, then dwindles quickly.

Here is a list of what seems to be the general consensus. Remember, nothing is better than a well placed shot.

Small Sized Game - 25 ft-lbs

Medium Sized Game (Deer, antelope, etc.) - 25-40 ft-lbs

Large Sized Game (Elk, Moose, Black Bear) - 50-65 ft-lbs

Dangerous/Tough Game (Cape Buffalo, Grizzly, etc.) - 65 ft-lbs and above

Approximate Arrow Weight Calculator
Enter the appropriate value in each box and the results will be updated. .

Shaft Weight per inch (grains):
Arrow Shaft Length (inches):
Point Weight (grains):
Insert Weight (grains):
Nock Weight (grains):
Number of Vanes:
Vane Weight per vane (grains):
Wrap Weight (grains):