MP3Gain Volume Normalizer

Here's a really useful one I'm surprised I hadn't mentioned already for your toolbox..
MP3Gain is a free program providing a non destructive method of preparing your entire MP3 library to insure that every song or program will all playback at the same volume level.

"MP3Gain uses David Robinson's Replay Gain algorithm to calculate how loud the file actually sounds to a human's ears"

That song is too loud!

The next song is too quiet...

Why cant they be jussst right?

They all Can with MP3Gain....

Simply speaking, what MP3Gain does is take a whole folder of mp3s, or a group of individual selections, then analyzes them and reports the variances in the group.

It also specifically indicates for you in red which of the individual songs or programs are clipping.

You then set what volume level you prefer them to be. The default is set at 89db, which is usually the optimum level to prevent distortion, but you can adjust as desired.

Next click on the Gain button, and let it do it's stuff. It doesn't reprocess the MP3, it simply tags them for playback at a level comparable to he rest o the library. Upon completion, the entire group of mp3s are normalized, so all will play back at an equal volume.
Now a nice even output is achieved in any player.

"What does MP3Gain do? MP3Gain automatically adjusts mp3s so that they all have the same volume."

What's so nice about MP3gain, is that the changes you make are completely reversible, and you can experiment and if you don't like the results, you can easily revert back to the way it was. The process is lossless, no actual changes are being made to the mp3, it only tells the mp3 how loud to play.
Using the program is pretty straight forward and it's easy on the resources, so it can be ran even on the oldest of computers.

Download MP3Gain:
http://mp3gain.sourceforge.net/

If you'd like a tutorial, here's one to get you going:
https://www.lifewire.com/how-to-normalize-mp3-files-2438861