How much coffee do I need to grind per 4 cups of coffee?
The answer is that it will depend on your personal preference for the strength of your coffee, the beans themselves, the type of brewing, and so on.  Many coffee bean bags have a reference on the side of them.

The standard guideline for most medium roast coffee bean bags is 2 tablespoons per 6 fl. oz. (3/4 cup in your 8oz liquid measuring cup).

The Specialty Coffee Association of America has some interesting info on this, per this link.  


  What the Specialty Coffee Association of America (SCAA) has to say:
  
  A cup is defined as 6 ounces of water before brewing. This will produce 5.33 ounces of brewed coffee. Or 125 ml &amp; 110 ml for Euro style coffee makers
  
  The SCAA defines 10 grams or .36 oz per cup as the proper measure for brewed coffee if using the American standards. If using Euro standards the measure is 7 grams per 125 ml.
  
  To further confuse things I will add a few more measures:
  
  3.75 oz per 1/2 gallon
  
  55 grams per liter
  
  2.25 gallons per 1 lb.
  
  If you want to know more check the SCAA's web page at www.scaa.org.