Enter a pellet's weight in grains and its velocity in feet per second to get foot-pounds of energy (FPE) and joules, calculated live as you type. Switch to Compare to check FPE across a few pellets side by side.
Foot-pounds of energy is the kinetic energy a pellet carries when it leaves the muzzle. It combines weight and velocity into a single number, which matters because velocity alone is misleading, a very light pellet can post an impressive FPS number on the box while carrying less actual energy than a heavier pellet moving slower. FPE is what actually determines how a rifle performs on pest control, hunting, or just punching a can.
You'll need a chronograph to get a real velocity reading. Most chronographs use two sensors spaced a known distance apart; the device times how long a pellet takes to cross both, then calculates FPS from that. Shooting over a chronograph with your actual hunting or target pellet, not just the lightest alloy pellet that came with the rifle, gives you a realistic number to plug into this calculator.
Switch the calculator above to Compare to check FPE across a few pellet weights at once, useful when you've chronographed a couple of pellet brands through the same rifle and want to see how weight and velocity trade off. Add up to four pellets side by side.
These are general reference points pulled from common airgun hunting guidance, not hard rules. Shot placement and range affect a clean, humane result more than raw power does, and legal power limits vary by country and state, always check current regulations where you live.
Some countries regulate airgun power specifically by FPE. The UK, for example, sets 12 FPE as the threshold above which a rifle requires a firearms certificate. Rules like this change over time and vary by jurisdiction, so treat any specific number here as a starting point, not a final answer.
This calculator is free to embed anywhere, including WordPress, no plugin required. Paste the code below into a Custom HTML block (or anywhere in your page's HTML):
<iframe src="https://airgunone.com/embed/airgun-fpe-calculator.html" width="100%" height="575" style="border:1px solid #c9c0a5;max-width:420px;" title="Airgun FPE Calculator"></iframe>In WordPress specifically: add a Custom HTML block to your page, paste the code above into it, and publish. That's it, no account, no API key, and no plugin needed.