I'm using Google's Traffic Estimator to gauge how many users I can acquire in a month, but I'm not sure how accurate it is. Also, I'm not sure if it includes Global or US traffic.

Does anyone have experience with this?

Here's an example of what I'm looking at: https://adwords.google.com/select/TrafficEstimatorSandbox?save=save&keywords=hacker%20news%0A%22hacker%20news%22%0A[hacker%20news]%0Ahacker%20newss%0A%22hacker%20newss%22%0A[hacker%20newss]&currency=USD&language=en