I built this Arrow Performance Calculator to make it easier to see how arrow speed, kinetic energy, and momentum work together with your bow. It shows how changes to your bow setup and finished-arrow weight affect performance, so you can compare possible builds and make better hunting-arrow decisions.
Enter your bow setup and finished-arrow weight, and the calculator estimates launch and downrange speed, kinetic energy, and momentum. It also finds your Everyday Formula Target and compares nearby arrow weights so you can see the tradeoffs before you build.
Where This Fits in the Everyday Arrow System
This is Step 2 of the Everyday Arrow System. Step 1 helps you find a practical target arrow weight. Here, you compare how that target works with your bow: speed, kinetic energy, momentum, and downrange performance. Then Step 3, the Hunting Arrow Trajectory Calculator, shows how the exact setup fits your zero, vertical window, rise, drop, and ranging margin.
Build Your Setup
Enter your bow’s IBO rating, draw length, and actual peak draw weight. Then add the complete arrow weight, bowstring accessory weight, and shooting distance; the results update when you change an input.
Before testing any suggested arrow weight, check your bow maker’s minimum finished-arrow-weight requirement.
How to Use the Arrow Performance Calculator
- Enter the bow’s IBO rated speed. Find this number in the bow manual or on the maker’s specification page. Use the listed IBO speed, not the speed of your current arrow.
- Enter your draw length and actual peak draw weight. Use the bow’s measured settings. Do not rely only on the number printed on the limbs. A bow shop can measure both if you are unsure.
- Enter the complete finished-arrow weight. Weigh the arrow as it will be shot on a digital grain scale. Include the shaft, insert, point, nock, vanes, wrap, and every other attached part.
- Enter the weight added to the bowstring. Include the peep, D-loop, silencers, and other string parts. Use measured or listed component weights when possible. Keep this total separate from arrow weight.
- Enter your normal shooting distance. The calculator uses it for the downrange estimate. It also uses it in the Everyday Formula adjustment.
- Build the comparison. Review your current arrow, the Formula Target, and nearby weights. Use Download Comparison CSV to save the table.
How to Read Your Results
Quick guide to the units
- FPS means feet per second and shows arrow speed.
- Grains measure arrow and component weight.
- Ft-lbs means foot-pounds and shows kinetic energy.
- Slug-ft/s is the unit used for momentum.
Launch speed, kinetic energy, and momentum
Launch speed is the estimated speed as the arrow leaves the bow. Kinetic energy comes from arrow weight and speed, while momentum uses mass and speed without squaring the speed. Read all three numbers together.
Downrange performance
This section estimates the speed left at your chosen distance. That speed is then used to find downrange kinetic energy and momentum, so you can compare the same arrow at launch and downrange.
Use the launch-speed result—or your measured chronograph speed—in the Hunting Arrow Trajectory Calculator for Step 3. There, you can choose the zero and vertical window that fit your own sight plan, then model rise, drop, time of flight, and the cost of a ranging mistake at close hunting or TAC and 3D distances.
Everyday Formula Target and Working Range
The Everyday Formula Target is the recommended balance point for your bow. It uses draw weight, IBO speed, draw length, and shooting distance. The Working Range is 25 grains below and above that target, and the calculator shows where your current arrow falls in that range.
What your Formula position means
- Below the range: Compare your arrow with a somewhat heavier build.
- Inside the range: Compare your current arrow with the center target.
- Near the target: Move into component, spine, and FOC planning.
- Above the range: Compare a somewhat lighter build unless you chose the extra weight for a clear reason.
Below or above the Formula range does not automatically mean unsafe or wrong. The range is planning guidance. Your bow maker’s minimum arrow weight remains the safety requirement.
I modeled 1,008 bow-and-arrow setups to test these same tradeoffs. The results explain why this calculator shows a Formula Target and nearby options instead of one magic arrow speed.
Arrow-weight comparison
Select Build Comparison to compare several arrow weights. Each row is a possible finished-arrow weight using the same bow settings. The table previews speed, kinetic energy, momentum, and the main tradeoff. It does not choose a shaft or component set.
Worked Example: A 450-Grain Arrow and the Formula Target
Enter this setup if you want to check the process:
- IBO speed: 340 fps
- Draw length: 27.5 inches
- Actual draw weight: 62 pounds
- Current finished arrow: 450 grains
- Bowstring accessory weight: 15 grains
- Normal shooting distance: 40 yards
| Build | Estimated Speed | Launch KE | Launch Momentum |
|---|---|---|---|
| Current: 450 grains | 258.9 fps | 66.99 ft-lbs | 0.517 slug-ft/s |
| Formula Target: 490 grains | 250.0 fps | 68.02 ft-lbs | 0.544 slug-ft/s |
This bow produces a 490-grain Formula Target with a 465–515-grain Working Range. The current 450-grain arrow is below that range.
Moving from 450 to 490 grains costs about 9 fps, while momentum rises and kinetic energy stays close. The comparison makes that tradeoff easy to see.
I use this comparison before I finish an arrow plan because it shows what a weight change may do before I buy or glue parts. It does not choose the shaft, parts, or tune for me; those steps come next.
What the Everyday Formula Target Means
The Formula starts with a grains-per-pound target based on draw weight. It then adjusts for IBO speed, draw length, and shooting distance to find a useful balance point for finished-arrow weight.
You do not have to finish at that exact weight. The Working Range lets you compare lighter and heavier choices; you can read the full method in The Everyday Arrow Weight Formula.
How the Speed, KE, and Momentum Estimates Work
These results are estimates. Bow design, tune, string parts, arrow parts, and shooting conditions can change the real result, so use a chronograph when you need measured launch speed.
Estimated arrow speed
The speed model starts with the bow’s IBO rating. It subtracts 10 fps for each inch below a 30-inch draw and 2 fps for each pound below 70 pounds.
It also subtracts 1 fps for each 5 arrow grains above 350 grains and another 1 fps for each 3 grains added to the bowstring. The result is then changed by an arrow-weight efficiency factor.
Estimated launch speed = [IBO speed − draw-length adjustment − draw-weight adjustment − arrow-weight adjustment − bowstring adjustment] × efficiency factor
The factor is 0.945 through 450 grains and 0.940 from more than 450 through 600 grains. It is 0.930 above 600 grains, which gives every build the same comparison method.
Arrow kinetic energy
KE = (Finished Arrow Weight × Speed²) ÷ 450,240
Arrow weight is in grains, speed is in feet per second, and the answer is shown in foot-pounds. Speed has a large effect because it is squared.
Arrow momentum
Momentum = (Finished Arrow Weight × Speed) ÷ 225,218
The answer is shown in slug-ft/s. Momentum changes with both weight and speed, so a heavier arrow can gain momentum even when it loses speed.
Downrange speed, KE, and momentum
The downrange model uses a weight-based rate of speed loss. Lighter arrows lose more speed per yard in the model, while heavier arrows lose less. The estimated downrange speed is then used for KE and momentum.
Find the Best Balance for Your Bow
A lighter arrow is usually faster and has a flatter path, while a heavier arrow is usually slower and has more momentum. Kinetic energy may rise, fall, or stay close because both weight and speed are part of that formula.
I do not judge an arrow by one number; I compare the full set of results. Then I plan a build that can reach the target weight with the right spine, FOC, parts, and tune.
Stay lethal,
– Mike
Frequently Asked Questions
How accurate is an arrow speed calculator?
It gives you a steady estimate from the details you enter. Bow design, tune, string parts, and actual arrow weight can change the measured speed, so use a chronograph when you need the real launch speed.
How is arrow speed estimated from IBO speed?
The calculator starts with the bow’s IBO rating, then adjusts for draw length, draw weight, arrow weight, and bowstring weight. An arrow-weight factor is applied at the end.
How does arrow weight affect speed, kinetic energy, and momentum?
More arrow weight usually lowers speed and raises momentum. Kinetic energy may not move the same way because speed is squared, so use the table to compare the full result.
What is the difference between kinetic energy and momentum?
Kinetic energy uses weight and speed squared, while momentum uses weight and speed. They show different parts of the same bow-and-arrow setup, so read them together.
What is the Everyday Formula Target?
It is the recommended finished-arrow-weight balance point for your bow. It uses draw weight, IBO speed, draw length, and shooting distance, with a Working Range 25 grains below and above the target.
Do I need to build at the exact Formula Target?
No. The target is the center of a useful range, but shaft spine, FOC, available parts, arrow flight, and tune also matter. Use the target to guide the build, then test the finished arrow.
CONTINUE THE ARROW SYSTEM
Your Next Steps
You have compared the target and nearby arrow weights, so the next step is turning that target into a complete arrow plan. Get the free Arrow Build Worksheet to record your target, candidate components, and calculator results before you buy or assemble parts.
⚖️ Plan Your Finished Arrow Weight
Add the shaft and every arrow part. Set a working FOC target before you lock the parts together.
🏹 Check Dynamic Spine
Make sure the planned shaft fits the bow, arrow length, and front weight.
🧭 Measure Arrow FOC
Check a useful mock-up when possible. Measure the finished arrow again after the build.
🔧 Follow the Arrow Build Guide
Choose the parts, build the arrow, tune it, and test the final setup.
🏹 Part of the Everyday Arrow System
Build the arrow as a system, then verify it with weight, FOC, tune, speed, and real shooting.
Want to see exactly what I’m carrying this season? Check out my Personal Bowhunting Gear List for 2026
