Coffee ratios are the amounts of coffee and water recommended within the industry for brewing coffee that will satisfy most coffee drinkers. However, these ratios are subjective and individual coffee drinkers will develop their own preferences.
Once a desired coffee to water ratio is determined, using a scale to weigh the coffee makes it easier to maintain consistent results. Alternatively, you can establish the number of teaspoons or tablespoons of coffee for a fixed amount of water, although this method is less precise.
French Press and Pour Over methods of brewing typically require more coffee than Drip methods to achieve the same result.
The ratios recommended within the industry are 1 gram of coffee to 14-18 grams of water. Of course, less water means a stronger coffee. For Espresso, the recommended ratio is 1 gram of coffee to 2 grams of water.
Coffee to Water Ratios and approximate yield from a 12 ounce / 340 gram bag of coffee are provided here. (See below for Espresso.)
1:14 = 2.0 grams of coffee per 1 oz. water. 340g/2.0 = 170 oz./ 6 oz. = 28 cups // 8 oz. = 21 cups (higher strength coffee)
1:15 = 1.9 grams of coffee per 1 oz. water. 340g/1.9 = 179 oz./ 6 oz. = 30 cups // 8 oz. = 22 cups (higher-medium strength coffee)
1:16 = 1.8 grams of coffee per 1 oz. water. 340g/1.8 = 189 oz./ 6 oz. = 31 cups // 8 oz. = 23 cups (medium strength coffee)
1:17 = 1.7 grams of coffee per 1 oz. water. 340g/1.7 = 200 oz./ 6 oz. = 33 cups // 8 oz. = 25 cups (lower-medium strength coffee)
1:18 = 1.6 grams of coffee per 1 oz. water. 340g/1.6 = 212 oz./ 6 oz. = 35 cups // 8 oz. = 26 cups (lower strength coffee)
For Espresso:
1:2 = 14 grams of coffee per 1 oz. water. 340g/14 = 24 oz. / 2oz. = 12 cups // 4 oz. = 6 cups (very high strength)