Enter a known energy figure in foot-pounds (FPE) and a pellet's weight in grains to back-calculate its velocity in feet per second and meters per second, live as you type. Switch to Compare to check velocity across a few pellets side by side.
FPS is the number every manufacturer prints on the box, and it's also the least useful number on its own. Two rifles can post identical FPS figures and deliver very different power, since that FPS rating is almost always measured with the lightest possible alloy pellet, often 5–7 grains, chosen specifically because a lighter pellet goes faster for the same amount of stored energy. Load a real hunting-weight pellet at 14–16 grains into that same rifle and the velocity drops significantly, even though the energy behind it barely changes.
This calculator works in reverse from our FPE calculator: instead of entering a chronographed velocity to find energy, you enter a known or target energy figure and a pellet weight to see what velocity that combination actually produces. That's useful for sanity-checking a manufacturer's advertised FPS claim once you know the rifle's real energy output, or for figuring out roughly how fast a different pellet weight will travel in a rifle you already own.
For picking a pellet weight or judging power for hunting and pest control, FPE is the more meaningful figure, it's what actually determines stopping power. FPS matters more for flatter trajectory and less wind drift at longer range, which is why target and field-target shooters often care about velocity specifically, separate from raw energy. Most shooters are better served checking FPE first with our FPE calculator, then using this tool if they specifically need the velocity number too.
Switch the calculator above to Compare to check velocity across a few energy and weight combinations at once, useful for seeing how different pellet weights will perform at a known power setting. Add up to four pellets side by side.
Also 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-fps-calculator.html" width="100%" height="580" style="border:1px solid #c9c0a5;max-width:420px;" title="Airgun FPS 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.