Bow FPS Calculator

This calculator helps archers determine the speed of their arrows in feet per second (FPS) based on bow specifications, arrow parameters, and environmental factors.

Draw Weight (lbs) The force required to pull the bowstring back, typically 30-80 lbs for most bows

Draw Length (inches) How far the bowstring is pulled back, typically 24-30 inches for most archers

Arrow Weight (grains) The total weight of the arrow including point, shaft, and fletching

Bow Type

Let-off (%): 65 Percentage of weight reduction at full draw (primarily for compound bows)

String Material

Temperature (°F) Environmental temperature affecting string performance

Quick Examples:

How to Use This Calculator

Enter your bow's draw weight in pounds (found on bow limbs or manufacturer specs)
Input your draw length in inches (measure from nock point to pivot point plus 1.75")
Enter the total arrow weight in grains (including point, shaft, and fletching)
Select your bow type and string material from the dropdown menus
Adjust the let-off percentage if using a compound bow
Input the current temperature for more accurate results
Click Calculate to see your arrow speed in FPS and kinetic energy

Formula Used

FPS = (DW × DL × EF) / (AW ÷ 100)

Where:

FPS = Arrow speed in feet per second
DW = Draw Weight (lbs)
DL = Draw Length (inches)
EF = Efficiency Factor (based on bow type, string material, and let-off)
AW = Arrow Weight (grains)

Kinetic Energy (ft-lbs) = (Arrow Weight × FPS²) ÷ 450,240

Example Calculation

Real-World Scenario:

An archer wants to calculate the speed of their arrow for a compound bow setup used for hunting whitetail deer.

Given:

Draw Weight = 70 lbs
Draw Length = 28 inches
Arrow Weight = 425 grains
Bow Type = Compound Bow
String Material = Fast Flight
Let-off = 80%

Calculation:

First, determine the Efficiency Factor (EF): For a compound bow with Fast Flight string and 80% let-off, EF = 0.95

FPS = (70 × 28 × 0.95) / (425 ÷ 100) = (1,860) / 4.25 = 438 FPS

Result: The arrow travels at approximately 438 feet per second with 181 ft-lbs of kinetic energy, which is sufficient for hunting medium-sized game.

Why This Calculation Matters

Practical Applications

Determining effective hunting range for different game animals
Selecting appropriate arrows for your bow setup
Optimizing bow setup for target shooting competitions
Estimating arrow trajectory for different shooting distances
Comparing performance between different bow configurations

Key Benefits

Helps ensure ethical hunting with sufficient kinetic energy
Improves accuracy by understanding arrow speed and trajectory
Saves money by selecting the right arrows before purchasing
Optimizes equipment for specific shooting scenarios
Provides baseline data for bow tuning and maintenance

Common Mistakes & Tips

Many archers only consider the shaft weight when calculating total arrow weight. For accurate results, include the weight of the point, insert, nock, fletching, and any additional components like lighted nocks or arrow wraps. Use a grain scale to measure the complete arrow assembly.

Temperature significantly affects string performance and arrow speed. Cold temperatures make strings less efficient, reducing FPS. For hunting in cold conditions, consider that your actual arrow speed may be 5-15 FPS lower than calculated at room temperature. Always test your setup in conditions similar to when you'll be hunting.

Manufacturer-advertised speeds are typically achieved with very light arrows and ideal conditions. Real-world performance with hunting-weight arrows is usually 20-50 FPS slower than advertised. Our calculator provides more realistic estimates based on your specific setup and conditions.

Frequently Asked Questions

For hunting, kinetic energy is often more important than pure FPS. Generally, 40 ft-lbs is sufficient for small game like rabbits, 45-55 ft-lbs for deer-sized game, and 65+ ft-lbs for larger game like elk. Most modern compound bows produce 280-320 FPS with hunting arrows, which provides adequate kinetic energy for most North American game when properly matched with the correct arrow weight.

Arrow weight has a significant impact on speed. For every 5 grains of arrow weight change, you can expect approximately 1-2 FPS change in the opposite direction. Lighter arrows fly faster but have less kinetic energy and momentum, making them less effective for hunting and more affected by wind. Heavier arrows fly slower but retain energy better and penetrate deeper.

This calculator provides estimates based on mathematical formulas and efficiency factors. While it's generally accurate within 5-10% of actual measured speeds when all inputs are correct, nothing replaces actual measurement with a chronograph. For competitive archery or when precise speed is critical, always verify with a chronograph. This calculator is excellent for comparing setups, selecting arrows, and estimating performance before purchasing equipment.

References & Disclaimer

Archery Performance Disclaimer

This calculator provides estimates based on mathematical formulas and industry standards. Actual arrow speed may vary due to factors including but not limited to: bow condition, string age and stretch, shooting form, release method, and environmental conditions. Always verify actual arrow speed with a chronograph before hunting or competing. The calculator is not a substitute for professional archery instruction or equipment tuning.

References

Archery Trade Association Technical Standards - Industry standards for bow performance testing and measurement
Pennsylvania Bowhunters Educational Manual - Comprehensive guide to arrow speed, kinetic energy, and hunting performance
Outdoor Life: Understanding Arrow Speed and Kinetic Energy - Detailed analysis of arrow performance metrics for hunting

Accuracy Notice

This calculator provides estimates based on standardized formulas and efficiency factors. Individual bow performance may vary by ±10% from calculated values due to manufacturing tolerances, string material variations, and other factors. For competitive archery or hunting applications where precise performance is critical, always verify actual arrow speed with a chronograph.

About the Author

Kumaravel Madhavan

Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.

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