# How many food calories am I eating?

Computes the calories (kcal and kJ) in a portion or a weight of 154 common foods, from the energy values of the USDA SR Legacy food composition database.

- Page: https://www.acalculator.org/food/food-calorie-calculator
- JSON spec: https://www.acalculator.org/food/food-calorie-calculator.json
- Version: 0bcabd7a286b

## Default answer

Example with the default inputs (Food group Fruits and juices, Food Banana, raw, Measure by Portions, Number of portions 1): Banana, raw: 1 medium banana (118 g) has about 105 calories.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| g | Food group | The group the food is listed under. |
| fruit | Food | The food, from the group fruits and juices. |
| veg | Food | The food, from the group vegetables. |
| grain | Food | The food, from the group grains, rice and cereal. |
| bread | Food | The food, from the group bread and baked goods. |
| dairy | Food | The food, from the group dairy and eggs. |
| meat | Food | The food, from the group meat and poultry. |
| fish | Food | The food, from the group fish and seafood. |
| nuts | Food | The food, from the group beans, nuts and seeds. |
| sweet | Food | The food, from the group oils, sweets and sauces. |
| snack | Food | The food, from the group snacks and fast food. |
| drink | Food | The food, from the group drinks. |
| by | Measure by | Count household portions (such as 1 medium banana) or type a weight. |
| n | Number of portions | How many of the food’s household portions you eat; fractions such as 0.5 are fine. |
| w | Weight eaten | The weight of the food you eat, as eaten (cooked foods are weighed cooked). |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| calories | Calories | Energy in kilocalories (the Calories on a food label): kcal per 100 g × grams eaten ÷ 100. |
| kj | Energy in kilojoules | The same energy in kilojoules: kcal × 4.184. |
| per100 | Calories per 100 g | The food’s energy per 100 grams in USDA SR Legacy. |
| grams | Grams eaten | The weight eaten: portions × the portion weight, or the typed weight. |
| eaten | Amount | What the calories are for: the portions with their weight, or the weight in grams. |
| food | Food | The food’s short name. |
| ndb | USDA NDB number | The food’s number in USDA SR Legacy, to look it up in FoodData Central. |

## Method

calories (kcal) = energy per 100 g × grams eaten ÷ 100; grams eaten = portions × portion weight, or the typed weight; kJ = kcal × 4.184.

## Assumptions

- Energy values and portion weights are from USDA SR Legacy (April 2018), the final release of the USDA National Nutrient Database for Standard Reference; it is frozen, so the values do not change.
- The list holds 154 common foods. Values are averages for the food as described (raw, cooked, drained); a brand or recipe can differ.
- Portions are the household measures in SR Legacy, such as 1 medium banana (118 g). Weights are of the food as eaten.
- Calories here are kilocalories, the unit food labels call Calories; 1 kcal = 4.184 kJ.

## Worked examples

1. g = fruit, fruit = 9040, by = portion, n = 1 gives calories = 105.02, per100 = 89, grams = 118, eaten = 1 medium banana (118 g), ndb = 09040. Source: USDA FoodData Central, SR Legacy 09040 Bananas, raw: 89 kcal per 100 g; 1 medium (7" to 7-7/8" long) = 118 g, https://fdc.nal.usda.gov/fdc-app.html#/food-details/173944/nutrients.
2. g = dairy, dairy = 1123, by = portion, n = 2 gives calories = 143, kj = 598.312, grams = 100, eaten = 2 × 1 large egg (50 g). Source: USDA FoodData Central, SR Legacy 01123 Egg, whole, raw, fresh: 143 kcal per 100 g; 1 large = 50 g, https://fdc.nal.usda.gov/fdc-app.html#/food-details/171287/nutrients.
3. g = grain, grain = 20045, by = weight, w = 0.25 gives calories = 325, grams = 250, eaten = 250 g. Source: USDA FoodData Central, SR Legacy 20045 Rice, white, long-grain, regular, enriched, cooked: 130 kcal per 100 g, https://fdc.nal.usda.gov/fdc-app.html#/food-details/168878/nutrients.
4. g = nuts, nuts = 12061, by = portion, n = 1.5 gives calories = 246.21975, grams = 42.525, eaten = 1.5 × 1 oz (23 almonds) (28.35 g). Source: USDA FoodData Central, SR Legacy 12061 Nuts, almonds: 579 kcal per 100 g; 1 oz (23 whole kernels) = 28.35 g, https://fdc.nal.usda.gov/fdc-app.html#/food-details/170567/nutrients.

## FAQ

### How do I work out the calories in a food?

Find the food’s energy per 100 grams, multiply by the grams you eat, and divide by 100. A medium banana weighs 118 g and bananas have 89 kcal per 100 g, so it has 89 × 118 ÷ 100 = 105 calories.

### Where do the calorie values come from?

From SR Legacy, the final release (April 2018) of the USDA National Nutrient Database for Standard Reference, published in FoodData Central. It is public domain and no longer changes. Each food shows its NDB number so you can look it up there.

### Are calories and kilocalories the same?

On food labels, yes. The Calories on a label are kilocalories (kcal). In kilojoules, used on labels in many countries, 1 kcal = 4.184 kJ, so 100 kcal is 418.4 kJ.

### Should I weigh food raw or cooked?

Weigh it the way the food is described. Cooked rice, pasta and meats in the list are for the cooked food, so weigh them cooked; raw fruits and vegetables are for the raw food. Cooking changes the weight, mostly by losing or taking up water, so a raw weight with a cooked value gives the wrong answer.

### Why is my food not in the list?

The calculator holds 154 common foods to keep the page fast. For other foods, the Nutrition Facts label gives calories per serving, and FoodData Central lists thousands more foods with their energy per 100 g, which you can use with the same formula.

### How accurate are the calories?

They are averages. A food’s energy varies with variety, ripeness, recipe and brand, and portion sizes vary too, so treat the answer as a good estimate, not an exact count. Weighing your food gives a closer answer than counting portions.

## Sources

- U.S. Department of Agriculture, Agricultural Research Service. FoodData Central: SR Legacy, April 2018 (energy, nutrient 1008, kcal per 100 g; household portion weights). Public domain. https://fdc.nal.usda.gov/
- USDA FoodData Central, Download Datasets (SR Legacy, April 2018, CSV). https://fdc.nal.usda.gov/download-datasets/
- NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B (calorie, thermochemical = 4.184 J exactly). https://www.nist.gov/pml/special-publication-811