This app was mentioned in 3 comments, with an average of 1.00 upvote
If you have an Android phone, I personally use this app. If you have an iPhone, there's likely one on the app store, but I don't know if it would be free or not.
Because of Joule creep, the converted numbers aren't always the exact real numbers, but they're usually close enough for most people to get an idea of what it should be shooting with a given weight
1.8j for a .25g @ 395fps.
Since when, and this I had saved on my phone until I found out they had a mobile app the other day. Idk I am a numbers man. I am cool either way, but when we break it down TM is hitting ~.84 joules stock lol. I just like having a standard when talking teching issues, because I shoot mostly .28s and someone may not shoot the same weight, but I can get pretty good idea of what they are shooting compared to me by using joules. I have done it enough I got the chart in my mind lol. I am just sharing, because I shit a brick when I first started using them. Like I found the standard boys! Mostly the feilds I played at started going by joules to help avoid joule creep. Plus its just neat to be the guy who can tell your buds what they will shoot with different weights.