How to Calculate Arrow Speeds

An archer must know the speed of his arrow to calculate how much the arrow will fall after it leaves the bow and whether the bow and arrow combination will be effective against game. There are two ways to find arrow speed. The archer can use a chronograph for the best accuracy or he can use a method that measures the drop of the arrow shot from two different distances.

Things You'll Need

  • Bow
  • Arrow
  • Chronograph
  • Target
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Instructions

    • 1

      Use a chronograph. A chronograph consists of two rectangular or triangular, hollow frames to signal the central unit when an object flies inside them and a central computer to analyze the data. Set it up with a backstop, and place the two traps the proper distance away from each other. Shoot an arrow through both traps and the computer will tell you the arrow speed.

    • 2

      Shoot a number of arrows at a target 20 yards. Keep the arrow level when you shoot it. Try to keep the group small.

    • 3

      Move back to 40 feet and fire another group, keeping the arrow level before the shot. Find the average center for both groups.

    • 4

      Measure the distance dropped between the two groups, from the 20-yard distance group to the 40-yard distance group.

    • 5

      Consult the chart below. The faster the arrow goes, the less it drops so, a shorter distance means a faster arrow.

      28.7 inch difference = 220 feet per second (fps) arrow speed

      24.2 inches = 240 fps

      20.6 inches = 260 fps

      17.7 inches = 280 fps

      15.5 inches = 300 fps

      13.6 inches = 322 fps

      12.8 inches = 330 fps