I found a few old threads that talked a little about this, but I am a bit confused.  Some people don't like dredging up old threads, so here is a new one.
 
I have been operating under the assumption that modern mixing and mastering targets program levels that run fairly close to 0db, at least for the peaks.  That is how I have mixed most of my projects.
 
I just purchased Ozone 6 Advanced, which includes the Insight metering plug-ins.  (Interestingly, it seems this only works on the 32-bit version of the stand-alone Ozone app, and I think the 32-bit Ozone plug-ins don't have all the function of the 64-bit versions.  I may be wrong about that.)
 
Anyway, I pulled up the Insight preset for the US loudness levels.  I was shocked to find my entire program being deep into the red zone.  As I looked into this further, it appears there are new broadcast standards based on the LU algorithm (which is pretty similar to RMS).  But the standard for broadcast is way below the level I have been mixing.
 
I surmise that broadcasters now must adhere to this new standard, which means that they may have to normalize the sound levels downward when broadcasting.    I also surmise that recording studios are not necessarily adhering to those levels in the production of CDs or MP3s.  If I mixed at the new levels, I think my material would be much quieter than most of what you find on Youtube, for example.
 
So what is going on here?  What levels should be we mastering to?

I found one reference where a guy says he masters to Integrated LU of about -12, which is a lot louder than the new broadcast standard, and pretty much like mastering to peak around 0dB (depending on the music's dynamic range of course.).  I notice in Insight, three are different presets for broadcast and music production, with the settings for music production being much louder.
 
So does this mean we should carry on as usual, mastering toward the top of the scale, and let broadcasters deal with bringing the sound level down to the legal standards whenever they play the music over the air?
 
I assume things like Youtube and Soundcloud are not covered by the broadcast loudness regulations, right?

Sound on Sound published an excellent article on the subject.

That's a great article.  Thanks.
 
I guess there are lots of implications.  But at the simplest level, if a person wants to start working within the "LU" framework, a target of -16.5 integrated LUs (or thereabouts) is probably a good place to be today.  That is louder than the broadcast standard, but in line with Spotify and other services that normalize the loudness, so that is about the level Internet users will be conditioned to hear. 

Thanks for the link Craig. I think I remember reading that article a while ago too.
So it sent me searching out a BS-1770 compatible meter plug-in. Looks like they are $$$ like the TC electronic version. @ $500+  
Anyone found something similar? Or do I already have the tool with RMS. 
This is the main reason I master in Wave Lab is the ability to report average RMS level which I guess is the same  thing only a different calibration.
I have read that around -13 Db Average RMS is a sane level if you want to preserve dynamics. It's what I've used without issue for a long time now.  I believe these LOUD commercial releases are like down around -7Db average RMS therefore very little dynamics.  

This one is free http://www.meldaproductio...p?id=MLoudnessAnalyzer

Further reading same topic 
 
http://www.soundonsound.com/sos/sep11/articles/loudness.htm
 
Here's an answer to my question from this: 
 
Admittedly, measuring the signal's RMS value only gives information about the 'electrical' or 'physical' content of the audio file, not a measure of loudness as we perceive it. For that, we evaluate the 'integrated loudness', as defined by the EBU 3341 normative recommendation.
 

cparmerlee
I just purchased Ozone 6 Advanced, which includes the Insight metering plug-ins.  ....
 
.... What levels should be we mastering to?

I also use Ozone Advanced (5). I just did an album (for family and friends) where I kept the Loudness Unit to -16dB.
If I keep the Peaks at -6dB and have the RMS level just right during the mix, the LU usually just comes out to be -16dB.
 
Walt
 

I use the K-14 scale for my music. This gives sufficient headroom for just about anything. I don't worry all that much about LU's - they're related to RMS levels but make use of a different reference level. K-14 is simply based on 0 being -14db down from full digital swing. Just keep the normal levels in the yellow, and make sure your peaks stay in range and you're good to go.

johnnyV
RMS value only gives information about the 'electrical' or 'physical' content of the audio file, not a measure of loudness as we perceive it.

It seems that the Integrated LU number ends up being very close to the RMS number -- within 1 or 2.  I assume that was by intentional design so as not to force people to adopt a whole new frame of reference.
 
I just finished mastering a live show and tried to keep the tracks to -16 on the integrated LU scale.  But my peaks were very close to 0.  I guess I didn't compress very much.  I probably have been doing LU in the range of 11-14 without knowing it, so this isn't a radical change.