The Efficiency Ratio looks at two inputs: calories and alcohol by volume. It calculates the percentage of calories in a given beer (or other alcoholic beverage) derived from alcohol. In theory, the calories that don’t come from alcohol will make you gain weight and won’t give you the potential desired effects from drinking said alcoholic beverage. To calculate the Efficiency Ratio, we need to know the number of calories from alcohol (specifically ethanol). Here are the steps:

- Multiply the Alcohol by Volume (ABV) by 12 to get the volume of alcohol per 12 ounces
- Multiply by 29.5735 to get the millileters of ethanol per 12oz serving
- Multiply by ethanol’s density .789g/mL to get mass in grams
- Multiply the number of grams by 6.93 (ethanol’s calorie per gram)
- Now we have the calories resulting from alcohol in a 12 oz. serving. Divide that number by the total calories per 12oz for the Efficiency Ratio.