I know the other guys here have given you answers already, but they haven't really explained why the StarMeter is useful, and who it's actually for.

The StarMeter is not for the 99.9% of "nobody" actors (me and you) for pissing contests with each other so we see "whose is bigger". No reputable agent, manager, or casting director cares about an actor's individual StarMeter.

The StarMeter is a useful feature for higher-end casting companies and agencies to be able to gauge what caliber a project is. Again, less about the individual actor, more about the project as a whole.

When they look at a feature, for example, iMDBpro allows them to get a better sense of what "level" the movie is by showing extra details such as budget. A quick glance at the StarMeter of all involved actors can also give them a better sense of how important the project is. The overall/average StarMeter allows us to better (but not perfectly) gauge where a project stands next to all other projects.

That being said, any one actor's individual StarMeter can quickly become unreliable as it is purely based off of views, which can easily be bought or altered. Think of it like a statistics class you've taken. One sample size is not enough. But if you have enough samples, you can quickly start to see the bigger picture. This is how StarMeter is actually used.

All that being said, there probably is a very small window of StarMeter rankings that do matter to casting directors. Perhaps there's some magic number (like under 4000) that allows them to determine if a celebrity is an A-lister or B-lister or what have you.

But again, it's nothing most actors should ever be concerned about.