A cup of strawberries and a tablespoon of olive oil can weigh about the same, but one has about 50 calories and the other about 120. The difference is calorie density, the energy packed into each gram of food. It is determined mainly by how much water, fibre and fat a food contains. Water and fibre add weight but no calories; fat adds 9 calories per gram. Foods with low calorie density take up more space on the plate and in the stomach for the same calories, which is why this idea features in many weight-management programmes. This calculator turns a food label or recipe into calories per gram, per 100 g and per ounce, and tells you which of four density categories it belongs to.
How to use the calorie density calculator
- Enter the calories in the portion from the label or recipe.
- Enter the weight of that portion in grams, ounces, pounds or kilograms. Use the weight of the food as eaten, including cooking water.
- Optionally enter a calorie target to see how much of the food that is.
- Read the density, the category and the comparison.
Calorie density formula
Calories per 100 g = density × 100 · per ounce = density × 28.35
Weight for a target = target calories ÷ density
| Category (Rolls) | kcal per gram | Typical foods |
|---|---|---|
| Very low | under 0.6 | Non-starchy vegetables, most fruit, broth soups |
| Low | 0.6 – 1.5 | Cooked grains and beans, potatoes, lean dairy, lean fish |
| Medium | 1.5 – 4.0 | Meat, eggs, bread, cheese-based dishes |
| High | over 4.0 | Crackers, chocolate, nuts, cheese, oils, butter |
The categories are those used in Volumetrics by Barbara Rolls (Rolls B, The Volumetrics Eating Plan, 2007), and the effect of energy density on weight loss was tested in Ello-Martin JA et al., Am J Clin Nutr 2007;85:1465–1477. Energy per gram of macronutrient: fat 9, alcohol 7, protein and carbohydrate 4, fibre about 2 (FAO, 2003).
Worked example
100 g of roasted chicken breast contains about 165 kcal.
- Density = 165 ÷ 100 = 1.65 kcal/g, a medium-density food.
- Per ounce = 1.65 × 28.35 = 47 kcal.
- 500 calories of it weighs 500 ÷ 1.65 = 303 g (10.7 oz).
The same 500 calories of raw apple (0.52 kcal/g) weighs 962 g, nearly a kilogram.
Calorie density of common foods
Approximate values per 100 g from USDA FoodData Central, rounded; actual values vary by variety and preparation.
| Food (approximate, per 100 g) | Calories per 100 g | Calories per gram | Density category |
|---|---|---|---|
| Cucumber, raw | 15 | 0.15 | Very low density |
| Apple, raw | 52 | 0.52 | Very low density |
| Broccoli, raw | 34 | 0.34 | Very low density |
| Banana | 89 | 0.89 | Low density |
| Rice, white, cooked | 130 | 1.30 | Low density |
| Chicken breast, roasted, no skin | 165 | 1.65 | Medium density |
| Egg, hard-boiled | 155 | 1.55 | Medium density |
| Bread, white | 265 | 2.65 | Medium density |
| Cheddar cheese | 403 | 4.03 | High density |
| Almonds | 579 | 5.79 | High density |
| Butter | 717 | 7.17 | High density |
| Olive oil | 884 | 8.84 | High density |
Using calorie density
- Build meals around low-density foods. Vegetables, fruit, soups and legumes fill you up for few calories.
- Watch the high-density foods, do not ban them. A small amount of nuts or olive oil adds nutrients and flavour.
- Remember water. Cooking rice or pasta in water lowers density; drying fruit raises it.
- Check serving size on labels. Density is per weight, not per serving.
Related tools
To set a daily calorie target use the Calorie Calculator or Calorie Deficit Calculator; the Macro Calculator splits calories into nutrients, the Fiber Intake Calculator shows fibre needs and the Alcohol Calories Calculator covers drinks. For low-carb counting see the Net Carb Calculator.
This page is for information only and is not medical advice. Speak to a doctor about your own health, alcohol use, diet or exercise plans.
Sources
- Rolls B. The Volumetrics Eating Plan. HarperCollins, 2007.
- Ello-Martin JA, Roe LS, Ledikwe JH, Beach AM, Rolls BJ. Dietary energy density in the treatment of obesity: a year-long trial comparing 2 weight-loss diets. Am J Clin Nutr 2007;85:1465–1477.
- US Department of Agriculture. FoodData Central (nutrient values per 100 g).
- FAO. Food energy — methods of analysis and conversion factors. FAO Food and Nutrition Paper 77, 2003.
Frequently asked questions
What is calorie density?
Calorie density, or energy density, is the number of calories in a given weight of food, usually expressed in calories per gram. Foods rich in water and fibre, such as vegetables and fruit, have low density; foods rich in fat and with little water, such as oils, nuts and chocolate, have high density.
Why does calorie density matter?
Research by Barbara Rolls and colleagues finds that people tend to eat a similar weight of food each day. Eating foods of lower calorie density therefore lets you eat a satisfying amount for fewer calories, which helps with weight control (Ello-Martin et al., Am J Clin Nutr 2007;85:1465–1477).
What are the density categories?
In Rolls’ Volumetrics framework: very low density is under 0.6 kcal/g (non-starchy vegetables, fruit, broth soups), low is 0.6 to 1.5 (cooked grains, beans, lean dairy), medium is 1.5 to 4.0 (meat, bread, cheese-rich dishes) and high is over 4.0 (crackers, chocolate, nuts, oils).
Is a high-density food unhealthy?
Not necessarily. Nuts, olive oil and avocado are calorie-dense and also very nutritious. Density is a tool for portion awareness, not a measure of nutrient quality.
What is the maximum possible calorie density?
Pure fat has about 9 kcal per gram, and no food can exceed that by much. If a calculation shows more, check the weight and calories entered.