Free bowhunting tool
Arrow Kinetic Energy & Momentum Calculator
Enter your arrow weight and speed for instant kinetic energy and momentum, then see exactly what game your setup is suited to, from whitetail and elk to red stag, kudu and buffalo. The only arrow calculator that reads your numbers against real animals.
Total finished-arrow weight (250 to 750).
Measured or IBO speed (100 to 450).
What can you hunt with this?
Your setup against real game, worldwide. Tap an animal for the full verdict.
A general guideline built on the published bowhunting energy bands and penetration research, not a rule. Shot placement, a sharp broadhead and clean arrow flight matter more than any single number. Check your local minimum-energy regulations.
This calculator is one tap away in the field, free, with your whole hunt.
It is built into the free hunter app, alongside everything you need on the hunt and after it. No app store, no cost, and it all works offline deep in the bush.
How the calculator works
Kinetic energy and momentum both come from two numbers, your arrow’s weight in grains and its speed in feet per second. The formulas are the same ones used across archery:
The constants come from the physics: 7,000 grains to the pound and 32.174 ft/s² of gravity. That is why our numbers match the Easton and Realtree calculators to the decimal. We also show the metric equivalents, joules and kilogram-metres per second.
Kinetic energy vs momentum
Think of kinetic energy as the hammer: it does the work of driving the broadhead through hide, muscle and bone, and speed builds it fastest. Momentum is penetration potential downrange, what keeps a heavy arrow driving through once it meets resistance. Light, fast arrows win on energy; heavy arrows win on momentum. On big, heavy-boned animals momentum and a strong single-bevel broadhead often matter more than raw speed. The sweet spot is enough of both.
How much kinetic energy do you need?
A widely used bowhunting guideline sorts game by body size. It is a starting point, not a rule: a sharp broadhead and a well-placed, broadside shot matter more than a number.
| Game class | Kinetic energy | Examples |
|---|---|---|
| Small game | Under 25 ft-lbs | Rabbits, wild turkey, small antelope, roe deer |
| Medium game | 25 to 41 ft-lbs | Whitetail, mule deer, pronghorn, fallow, impala, springbok |
| Large game | 42 to 65 ft-lbs | Elk, red stag, black bear, kudu, wildebeest, sambar |
| Heavy & dangerous game | 65+ ft-lbs | Moose, bison, eland, Cape buffalo, water buffalo |
Use the calculator above to check your exact setup against individual species in North America, Europe, Africa and the Asia-Pacific.
Is my bow enough for…
Pick your quarry for the energy it needs and the setup to bring.
Put this calculator on your site
Run a hunting blog, club or shop? Drop the calculator into any page, free. It stays up to date automatically. Just keep the HuntDesk credit link.
<iframe src="https://www.huntdesk.co.za/tools/arrow-speed-calculator/embed" title="Arrow Kinetic Energy & Momentum Calculator" width="100%" height="820" style="border:0;max-width:520px" loading="lazy"></iframe>
<script>window.addEventListener("message",function(e){if(e.origin==="https://www.huntdesk.co.za"&&e.data&&e.data.type==="hd-arrow-height"){var f=document.querySelector('iframe[src="https://www.huntdesk.co.za/tools/arrow-speed-calculator/embed"]');if(f){f.style.height=e.data.height+"px";}}});</script>Method & sources
- The physics.Kinetic energy and momentum use the standard archery constants (7,000 grains per pound, 32.174 ft/s² for gravity), so results match the Easton and Realtree calculators to the decimal.
- The energy guidelines. The minimum kinetic-energy bands by game size are the long-established bowhunting guideline popularised by Easton Archery and widely used across the sport.
- The heavy-game refinement. For large, heavy-boned animals we weight the verdict toward momentum and arrow mass, following the penetration research of the Ashby Bowhunting Foundation (Dr. Ed Ashby), which found momentum, arrow weight and structural integrity, not raw speed, drive penetration through heavy bone.
- Speed figures. Arrow speed relates to the IBO and ATA rating standards published by bow manufacturers; a chronograph reading of your own arrow is always the most accurate.
- Regulations first. These are guidelines, not law. Always meet your local minimum draw-weight and kinetic-energy requirements, and let shot placement and a sharp broadhead lead every decision.
Maintained by the HuntDesk team. Last reviewed July 2026.
Frequently asked questions
How do you calculate arrow kinetic energy?
Kinetic energy in foot-pounds equals the arrow weight in grains multiplied by the arrow speed in feet per second squared, divided by 450,436. For example, a 420 grain arrow at 280 fps produces about 73 foot-pounds of kinetic energy.
What is arrow momentum and why does it matter for bowhunting?
Momentum equals the arrow weight in grains multiplied by speed in fps, divided by 225,218, giving a value in slug-feet per second. Momentum represents penetration potential downrange, what keeps the arrow driving through hide, muscle and bone. It favours heavier arrows, which is why momentum matters most on large, heavy-boned game.
Is kinetic energy or momentum more important?
Both matter. Kinetic energy is the hammer that drives the broadhead, and speed builds it fastest. Momentum is penetration potential, and heavier arrows carry more of it. On thin-skinned game either serves; on heavy-boned animals such as buffalo, eland, moose or wild boar, momentum and a strong single-bevel broadhead carry more weight. The best setup has enough of both.
How much kinetic energy do I need to bowhunt deer?
The long-standing bowhunting guideline puts medium game such as whitetail deer, mule deer, fallow and impala at roughly 40 foot-pounds and up, paired with a sharp, well-placed broadhead. Small game needs less; large game such as elk, red stag and kudu wants roughly 50 to 65 foot-pounds. These are guidelines, not rules, and shot placement matters more than any number.
How much kinetic energy do I need for elk, moose or buffalo?
Large game such as elk and red stag is commonly put at roughly 50 to 65 foot-pounds. Heavy and dangerous game such as moose, eland, bison and Cape buffalo is put at 65 foot-pounds and well up, with the emphasis shifting to momentum, heavy arrows and a single-bevel cut-on-contact broadhead for reliable penetration through heavy bone.
How do I find my arrow's speed?
The most accurate way is a chronograph, which reads true speed for your exact arrow and bow. Failing that, use your bow's IBO or ATA rating as a starting point and adjust down for your draw length, draw weight and total arrow weight, since heavier arrows and shorter draws shoot slower than the rated figure.