When You Can't Measure, Estimate Portions

An essential part of calorie counting is accurately estimating portion sizes. It is not difficult to do when you eat at home, but determining portions when you eat out is a bit harder.

Research shows that people of all ages, education levels and body weights erroneously underestimate their food portions by 20 to 200 percent. The United States Department of Agriculture (USDA) finds that adults typically underestimate consumption of grains, sweets and fats, and overestimate fruit, milk products, and servings of meat, poultry, fish, dry beans, eggs, and nuts. When it comes to vegetables, women overestimate and men underestimate their servings.

Training is Key

People can be trained to improve their knack for estimating portions. The key is to become familiar with the "estimating aids" and to practice your skills at home. These props will guide your visual estimations of food measurements: a deck of playing cards, a computer mouse, a tennis ball, half a baseball ball, a ping pong ball, cotton balls, an audiocassette tape, a light bulb, a 9-volt battery, and a standard-size hand. Practice by portioning out food and using the prop to estimate the measurement. Test your estimate by measuring the food and comparing the actual measurement to your estimates.

Props Used to Estimate Food Portions

The Grain Group
1/2 cooked cup rice ---- tennis ball
1 pancake (1 ounce or 5") ---- compact disc (CD)
1 piece of cornbread (2 ounces) ---- bar of soap
1 slice of bread (1 ounce) ---- audiocassette tape
1 cup of pasta/spaghetti (2 ounces) ---- a fist
1 cup of cereal flakes (1 ounce) ---- a fist

The Vegetable Group
1 cup green salad ---- baseball or a fist
1 medium baked potato (1 cup) ---- computer mouse or a fist
1/2 cup cooked broccoli ---- light bulb
1/2 cup serving ---- 6 asparagus spears; 7 or 8 baby carrots; 1 ear of corn on the cob

The Fruit Group
1/2 cup of grapes (15 grapes) ---- light bulb
1/2 cup of fresh fruit ---- 7 cotton balls
1 medium size fruit ---- tennis ball or a fist
1 cup of cut-up fruit ---- baseball or a fist
1/4 cup raisins ---- large egg

The Milk Group
1 1/2 ounces hard cheese ---- 9-volt battery or your index and middle fingers
1 ounce of processed cheese ---- your thumb
1 cup of ice cream ---- baseball

The Meat and Beans Group
2 tablespoons peanut butter (= 2 oz. meat) ---- ping-pong ball
1 teaspoon peanut butter (= 1/3 oz. meat) ---- fingertip
1 tablespoon peanut butter (= 1 oz. meat) ---- thumb tip
3 ounces grilled/baked fish or chicken ---- checkbook
3 ounces cooked meat, fish, poultry ---- your palm, a deck or cards or a cassette tape

Discretionary Calories

Fats, Sugars and Sodium
teaspoon butter, margarine ---- stamp, the thickness of your finger or knuckle to thumb tip
tablespoons regular salad dressing ping-pong ball

Snack Foods
1 ounce of nuts or small candies ---- one handful
1 ounce of pretzels ---- two handfuls
1/2 cup of popcorn ---- one man's handful
1/3 cup of popcorn ---- one woman's handful

Serving Dishes/Utensils
1/2 cup ---- custard cup or mashed potato scoop
1 1/2 cups ---- large cereal/soup bowl
1 1/2 cups of pasta, noodles ---- dinner plate, not heaped
1/2 cup of pasta, noodles ---- custard cup or mashed potato scoop


  • Young, LR, Nestle, M. Variations in perceptions of a "medium" food portion: implications for dietary guidance. J Am Diet Assoc 1998; 98: 639 - 641
  • Schwartz, J, Byrd-Bredbenner, C. The ability of young adults to estimate portion size and calorie content. Top Clin Nutr 2006; 21: 114-121.
  • Thompson, FE, Midthune, D, Subar, AF, McNeel, T, Berrigan, D, Kipnis, V. Dietary intake estimates in the National Health Interview Survey, 2000: Methodology, results, and interpretation. J Am Diet Assoc 2004;105: 352-363

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