How much money can I make with AdSense?

There’s just no easy answer to this question. Well, okay, there’s an easy
answer — it depends. But that easy answer isn’t really useful. The problem
is that several measurements impact your daily revenue from AdSense ads,
such as
Unique visits: A visitor is considered unique when she visits your Web
site the first time during a given period of time. Depending on the
metric — the measurement used to track visitors on your Web site —
that’s used, a visitor might be considered unique the first time he visits
your site in a 24-hour period, the first time in a week, or the first time
in an hour. For AdSense, the unique visits measurement is used to help
determine the click-thru rate for ads.
Click-thru rate (CTR) is the number of people who click an ad and are
taken to the Web page designated for the advertisement. This page is
usually a larger, more colorful ad, the opening page of a Web site, or a
page that displays more information about the product or service featured
in the ad.
Average click-through-rate (CTR): The CTR is the actual number of
visitors who click through an ad on your Web site. This is important
because you’re paid when users click your AdSense ads.
Average cost-per-click (CPC): The CPC is the amount that advertisers
pay each time someone clicks one of their ads. This number varies
widely and is dependent upon the cost of the keyword to which an ad is
related. For you, as an AdSense publisher, the CPC is the basis for how
much you’re paid.
Using these three measurements — measurements which are highly
variable — you can estimate how much you could make based on some
hypothetical numbers. For example, assume that your Web site gets 1,000
unique visits per day and that the average value of the ads that are displayed
on your site each day is $.25 per click (that’s the CPC). Finally, assume that
about 2 percent of your 1,000 visitors click through the ads on your site each
day. Now, you have numbers that you can work with.
With those hypothetical numbers in place, you can use this equation to estimate
how much you might make from your AdSense ads on a given day: