An amount of 3 3/4 cups of ground coffee is needed for a 30-cup pot. A standard ratio to brew a cup of coffee is two tablespoons for 6 ounces of water. Using this standard, it would take 60 tablespoons for a 30-cup pot. Converting this amount to cups is 3 3/4 cups of ground coffee.
The previously suggested coffee-to-water ratio of two tablespoons to 6 ounces of water is typical for a stronger cup of coffee. Reducing the ratio to one tablespoon of coffee to six ounces of water will yield a brew. This would translate to roughly 1.88 cups of coffee or between 1 3/4 and two cups of coffee for a 30-cup pot. Determining a weak or strong cup of coffee depends on taste preference and the variety of coffee being brewed.
Fresh, filtered water is recommended for optimum flavor. The method of grinding coffee also determines the quality of the brew. Some may use a French press, which requires a coarse grind. However, a fine grind is recommended for a shot of espresso, or a very strong black coffee. A drip coffee maker requires a medium-to-coarse grind to saturate the coffee without creating a scorched flavor.