Bow FPS Calculator

If you're into archery whether for hunting, target shooting, or just for fun knowing how fast your arrow flies is essential. Our Bow FPS Calculator is the perfect free tool to find out your arrow’s speed in FPS (feet per second), m/s (meters per second), or even km/h with just a few simple inputs.

Designed for archers of all levels, this calculator helps you estimate the performance of your compound bow, crossbow, or recurve bow without using expensive chronographs. It's quick, easy, and accurate.

What is Bow FPS?

FPS stands for feet per second, and it’s the standard unit used to measure how fast an arrow travels after being released from the bow. The faster the FPS, the flatter the arrow’s trajectory and the less it’s affected by gravity.

Your bow’s FPS is influenced by several factors:

• Draw weight (in pounds)
• Draw length (in inches)
• Arrow weight (in grains)
• String accessories (like silencers or dampeners)
• The bow’s IBO rating (factory-rated speed under ideal conditions)

How to Use the Bow FPS Calculator

To use the calculator, just enter the following values:

• IBO Rating: This is the manufacturer’s speed rating of your bow (usually based on 70 lbs, 30″ draw, and 350-grain arrows).
• Draw Length: Your personal draw length.
• Draw Weight: The weight you pull back.
• Arrow Weight: Total weight of your arrow.
• String Accessory Weight (optional): Additional weight on your string, like silencers.

After entering your details, the calculator gives you:

• Final FPS (arrow speed)
• Metric speed in m/s
• Speed in km/h
• Kinetic energy (in foot-pounds)
• Momentum (slug·fps)

Bow FPS Formula (How It Works)

We use the industry-accepted IBO standard formula for accuracy:

Arrow Speed (fps) = IBO + (Draw Length − 30) × 10 − (String Weight ÷ 3) + min(0, −(Arrow Weight − 5 × Draw Weight) ÷ 3)

Explanation:

• IBO: The base speed of your bow
• (Draw Length - 30) × 10: Every inch above or below 30″ changes speed by ~10 fps
• String Weight / 3: Every 3 grains on the string reduces speed by 1 fps
• Arrow Weight Adjustment: If your arrow is heavier than 5 grains per pound of draw weight, it reduces your speed

Example Calculation

Let’s say:

• IBO = 320 fps
• Draw Length = 28.5 inches
• Draw Weight = 70 lbs
• Arrow Weight = 425 grains
• String Accessory Weight = 0 grains

Speed = 320 + (28.5 − 30) × 10 − 0 ÷ 3 + min(0, −(425 − 350) ÷ 3)

Speed = 320 − 15 + 0 − 25

Speed = 280 fps

So your arrow would fly at 280 feet per second.

Final Verdict

Whether you shoot a compound bow, recurve, or crossbow, our Bow FPS Calculator gives you an accurate estimation of arrow speed. It's especially helpful if you're tuning your setup or choosing the right arrow for better accuracy and power.

Knowing your arrow speed is not just about numbers it helps you improve your aim, determine your range, and make ethical hunting decisions. No more guessing. Just calculate and shoot smarter.

FAQs

How many fps is a 70 pound bow?

It depends on the draw length and arrow weight. With standard conditions (30″ draw and 350-grain arrow), a 70 lb bow can shoot around 315–340 fps, depending on its IBO rating.

What fps is a 20lb bow?

A 20 lb recurve or beginner bow may shoot between 150 to 190 fps, depending on arrow weight and draw length.

Is 280 fps fast for a bow?

Yes! 280 fps is considered a great speed for hunting and target shooting. It provides a good mix of speed and kinetic energy for accuracy and penetration.

Can this calculator work for crossbows?

Yes, while IBO ratings don’t apply to crossbows, you can still estimate your arrow (bolt) speed by entering equivalent weight and draw specs.

Can I get arrow speed in km/h?

Yes! The calculator converts FPS to both m/s and km/h for your convenience.