Cooking at home

How to calculate calories in a homemade meal

Home-cooked food rarely has a barcode. The good news: you only need to do the maths once per recipe, and the method is simple.

Updated 26 October 2026 · 6 min read

In short

Add up the raw ingredients, including the oil.
Weigh the finished dish – or count equal portions – and divide.
Cooking changes weight, not calories: water in, water out.
Save the recipe so that next time you only log the portion.

The method in four steps

List every ingredient as it goes into the pot – ideally raw and dry, with the amount from the package or your measurement. Do not forget the oil or butter.
Add up the calories of all ingredients. This is the energy content of the whole dish.
Weigh the finished dish (subtract the weight of the empty pot), or divide it into equal portions and count them.
Divide: total calories ÷ total weight × your portion, or total calories ÷ number of portions.

Why does this work? Cooking moves water – pasta and rice absorb it, meat and vegetables lose it – but it does not create or destroy the calories you put in. The weight of the finished dish already includes all of those changes.

A worked example

Example: chicken and rice for the week
Ingredient (raw)	Amount	kcal
White rice, dry	250 g	913
Chicken breast, raw	500 g	600
Olive oil	2 tbsp (27 g)	239
Vegetables	per label	add yours
Total (without vegetables)		1,752

Suppose the finished dish in the pot weighs 1,450 g (your own measurement – it will depend on how long you cook it and how much water the rice absorbs).

Per 100 g: 1,752 ÷ 1,450 × 100 ≈ 121 kcal
A 400 g portion: ≈ 483 kcal
No scale? Divide the pot into four equal boxes: 1,752 ÷ 4 ≈ 438 kcal per box.

Values per 100 g come from USDA FoodData Central: dry white rice about 365 kcal, raw chicken breast about 120 kcal and olive oil about 884 kcal. Your products may differ slightly – use the label when you have it.

Raw vs cooked: the costly mix-up

The same food has very different values per 100 g depending on whether it is raw or cooked, because water is added or removed:

White rice: about 365 kcal dry vs about 130 kcal cooked.
Pasta: about 371 kcal dry vs about 158 kcal cooked.
Chicken breast: about 120 kcal raw vs about 165 kcal roasted (it loses water).

Logging 200 g of cooked rice with the "dry" entry would record about 730 kcal instead of about 260. Always match the entry to the state in which you weighed or estimated the food.

Tips for soups, stews and meal prep

Soups: weigh the full pot or measure the volume; a ladle of a known size makes logging easy.
Family meals: if several people eat from one pot, weighing your portion (or counting ladles) is fairer than "a quarter".
Fat that stays in the pan still counts for the dish unless you pour it away.
Batch cooking: calculate once on Sunday, label the boxes with the calories per box and log them in seconds during the week.

Frequently asked questions

Should I weigh food raw or cooked?

Either works, as long as you use the matching entry. For recipes, adding up raw ingredients and weighing the finished dish is the most reliable method.

Do calories change when food is cooked?

Cooking mostly changes the water content and therefore the weight, so the calories per 100 g change. The total energy you put into the pot stays practically the same.

How do I count calories in soup?

Add up all ingredients, measure the total volume or weight of the soup and divide. A ladle of known size makes portions easy to log.

Sources

This guide is general information for healthy adults, not medical advice. If you are pregnant, breastfeeding, have or have had an eating disorder, or need a therapeutic diet, talk to a doctor or registered dietitian.