The Effective Firearms Stopping Power Calculator provides up to six (6) indices of bullet performance.
For a visual example, please view the YouTube tutorial: https://www.youtube.com/watch?v=SZm-4Zc-qlo
Enter a muzzle velocity (feet per second) and bullet weight (grains) and it can display the bullet momentum and muzzle (kinetic) energy.
Enter the caliber and you can also display the Taylor Knock Out Factor (TKOF) and the Thorniley Stopping Power indices.
If you also enter bullet form, the Hatcher Relative Stopping Power value is also available (with the expanded value for hollow/soft point).
While all six values are available via the Internet, obtaining them would require visiting multiple web sites, which can be awkward while standing in a store evaluating ammunition options on the shelf.
Please send any questions, complaints, or corrections to firstname.lastname@example.org.