The Compound Bow FPS (Feet Per Second) Calculator is a tool designed for archers and bowhunters to estimate the speed of their arrows when shot from a compound bow. This calculator helps users understand how changes in bow settings and arrow configurations can impact the arrow’s flight speed, which is crucial for optimizing performance and accuracy. By inputting specific variables such as the IBO Speed, Draw Length, and Arrow Weight, the calculator provides an estimate of the arrow’s speed in feet per second. This information is valuable for making informed decisions about equipment adjustments and for tailoring the bow setup to the archer’s specific needs.
Formula of Compound Bow FPS Calculator
To calculate the FPS (Feet Per Second) speed of an arrow shot from a compound bow, use the following formula:
FPS = (IBO_Speed * (1 - (0.003 * (Draw_Length - 30)))) * (Arrow_Weight / 5)
Where:
FPSis the feet per second (speed) of the compound bow.IBO_Speedis the manufacturer’s advertised speed of the bow, usually measured at a specific draw length and draw weight.Draw_Lengthis the length of the draw in inches.Arrow_Weightis the weight of the arrow in grains (1 grain = 1/7000 pound).
This formula provides a basis for understanding how different factors affect the speed of an arrow, offering a way to predict performance outcomes based on measurable inputs.
Table for General Terms
| Term | Definition | Example Values |
|---|---|---|
| IBO Speed | The speed of an arrow shot from a bow under IBO standard conditions: 70 lbs draw weight, 30″ draw length, and a 350-grain arrow. | 280-350 FPS |
| Draw Length | The distance from the nock point to the throat of the grip plus 1.75 inches when the bow is at full draw. | 26″ – 31″ |
| Arrow Weight | The total weight of the arrow, including the point, shaft, fletching, and nock, measured in grains. | 350 – 500 grains |
| FPS (Feet per Second) | The speed at which the arrow travels from the bow. | Calculated based on formula |
Conversion Factors
For ease of use, here are some common conversion factors relevant to archery:
| Conversion | Factor |
|---|---|
| Inches to Centimeters | 1 inch = 2.54 cm |
| Pounds to Kilograms | 1 pound = 0.453592 kg |
| Grains to Grams | 1 grain = 0.06479891 grams |
These terms and conversion factors are essential for understanding and optimizing compound bow performance.
Example of Compound Bow FPS Calculator
Consider a compound bow with an IBO Speed of 320 FPS, a draw length of 28 inches, and an arrow weight of 400 grains. Using the formula provided, the calculated FPS would be:
FPS = (320 * (1 - (0.003 * (28 - 30)))) * (400 / 5)
This example demonstrates how to use the formula to estimate the speed of an arrow based on specific variables.
Most Common FAQs
IBO Speed refers to the International Bowhunting Organization’s standard for measuring the speed of a bow. It is important because it provides a benchmark for comparing the performance of different bows under standardized conditions.
Arrow weight directly impacts FPS; increasing the weight of the arrow decreases its speed, while decreasing the weight increases its speed. This relationship is crucial for optimizing arrow performance and achieving the desired balance between speed and penetration.
This calculator is specifically designed for compound bows. Different types of bows, such as recurve or longbows, have different mechanics and factors affecting their arrow speed, and thus would require different calculations.
