Estimating Your Liquid Calorie Intake

Brian Wansink, PhD, author of Mindless Eating has come up with a "10-20" rule for guesstimating the number of calories in a drink when a nutritional label is unavailable.

For most “thin” liquids such as juice, milk, soda, etc., figure 10 calories per ounce; for thicker drinks like shakes and smoothies, figure 20 calories per ounce.

For example, according to the 10-20 rule, a 20-ounce Pepsi from a convenience store soda fountain would contain approximately 200 calories.

This is a great tool for when you have no way of knowing the actual figures but remember, it's just an estimate. A quick online search turned up a calorie count of 250 for a 20-ounce Coke and 400 calories for a 32-ounce Pepsi, both higher than the 10-20 rule estimates.