It's hard to say exactly how much you'll earn with AdSense until you try it for yourself. AdSense earnings are dependent on many factors such as how much traffic you get, what type of content you provide, where your users are located, how you set up your ads, and so on.
Get an estimate
For an estimate, try the revenue calculator on the AdSense site. It calculates your potential annual revenue based on the content category of your site (arts & entertainment, finance, etc.) and the region where you get the most visitors. Bear in mind that this value is only an estimate.
Sign up for AdSense
The best way to find out how much you'll earn is to sign up and start showing ads on your site. AdSense is free of charge, and it's easy to get started.
When your account is up and running, you can sign in at any time to check your earnings. This information will give you an idea of how well the program is performing for you and how much you might expect to earn over time.