Energy Density Calculator (Food kcal/g)
Calculate the energy density of any food in kcal/g and kJ/g, compare portions, and classify foods as low, medium, or high energy density for weight management.
Food Energy Density Calculator
Use the calories (kcal) or kilojoules (kJ) for the portion you know (e.g., per serving).
Enter the weight that corresponds to the energy value above.
Use this to estimate calories in a different portion (e.g., 150 g instead of 100 g).
Results
Try common examples
Click a preset to see how energy density changes between foods.
What is energy density in food?
In nutrition, energy density is the amount of energy (calories or kilojoules) per unit weight of food, usually expressed as kcal per gram (kcal/g) or kJ per gram (kJ/g).
Two foods can have the same number of calories per serving but very different weights and volumes. The one with higher energy density packs more calories into each gram, so a small portion can still be very calorie-dense.
Basic formula
Let \(E\) be energy and \(m\) be mass (weight):
\[ \text{Energy density (kcal/g)} =
\frac{E_{\text{kcal}}}{m_{\text{g}}} \] \[ \text{Energy
density (kJ/g)} = \frac{E_{\text{kJ}}}{m_{\text{g}}} \]
To convert between kcal and kJ: \[ 1\ \text{kcal} = 4.184\ \text{kJ} \]
How to use the energy density calculator
- Enter energy: Type the calories or kilojoules for the portion you know (e.g., per serving from the label).
- Enter weight: Enter the corresponding weight and unit (g, kg, oz, or lb).
- Optional – serving size: Add a custom serving size to estimate calories in a different portion.
-
Click “Calculate”: The tool shows:
- Energy density in kcal/g and kJ/g
- Calories per 100 g
- Calories for your custom serving
- A category: low, medium, or high energy density
Typical energy density ranges
There is no single universal cutoff, but these ranges are commonly used in nutrition research:
| Category | Energy density (kcal/g) | Examples |
|---|---|---|
| Very low | < 0.6 | Most vegetables, broth-based soups, many fruits |
| Low | 0.6 – 1.5 | Starchy vegetables, legumes, whole grains, lean dairy |
| Medium | 1.5 – 3.0 | Bread, cheese, some meats, mixed dishes |
| High | > 3.0 | Nuts, oils, fried foods, sweets, chocolate |
Why energy density matters for weight management
Your stomach senses volume and weight more than calories. Low energy density foods let you eat larger portions for the same calories, which can:
- Increase fullness and satisfaction
- Make calorie control easier without strict portion sizes
- Help with long-term adherence to a diet
High energy density foods are not “bad” by default—they can be nutritious (e.g., nuts, olive oil). But they are easy to overeat, so portion awareness is important.
Worked examples
Example 1 – Boiled potato
Suppose 150 g of boiled potato contains 87 kcal.
\[ \text{Energy density} = \frac{87\ \text{kcal}}{150\ \text{g}} \approx 0.58\ \text{kcal/g} \] \[ \text{Calories per 100 g} = 0.58 \times 100 \approx 58\ \text{kcal} \]
This is a very low energy density food, which is why potatoes can be filling for relatively few calories when boiled or baked without added fat.
Example 2 – Chocolate bar
A 43 g chocolate bar contains about 230 kcal.
\[ \text{Energy density} = \frac{230\ \text{kcal}}{43\ \text{g}} \approx 5.35\ \text{kcal/g} \] \[ \text{Calories per 100 g} = 5.35 \times 100 \approx 535\ \text{kcal} \]
This is a high energy density food: a small bar contains as many calories as a large plate of vegetables or several pieces of fruit.
Energy density vs. nutrient density
It is important to distinguish between:
- Energy density: calories per gram.
- Nutrient density: vitamins, minerals, fiber, and other beneficial nutrients per calorie.
Ideally, you want foods that are nutrient-dense and not excessively energy-dense for your goals. For example:
- Nuts: high energy density, but also nutrient-dense and rich in healthy fats.
- Sugary drinks: high energy density, but low nutrient density.
- Vegetables: low energy density and high nutrient density.
Limitations and practical tips
- Energy density does not account for protein, fiber, or micronutrients, which also affect satiety and health.
- Cooking methods can change energy density (e.g., frying adds fat and calories).
- For weight loss, focus on patterns: more fruits, vegetables, whole grains, and lean proteins; fewer ultra-processed, high-fat, high-sugar foods.
- Use this calculator alongside your usual calorie tracking or meal planning tool.
FAQ
What is a good energy density for weight loss?
Diets emphasizing foods under about 1.5 kcal/g tend to support weight loss and maintenance. That usually means plenty of vegetables, fruits, legumes, and whole grains, with moderate amounts of higher energy density foods.
Can I use this for liquids and drinks?
Yes. You can enter the calories and weight (or approximate weight from volume, assuming 1 mL ≈ 1 g for water-like drinks). Many sugary drinks and alcohol have relatively high energy density compared to their satiety.
Is higher energy density always bad?
No. High energy density foods can be useful if you need to gain weight or have high energy needs (e.g., athletes, people with low appetite). The key is matching energy density to your goals and overall diet quality.