How to Calculate Calories in Food, Meals, and Recipes

What Does "Calculating Calories" Mean?

Calories (kcal) measure the energy a food provides to the body. Every food supplies energy based on its macronutrients:

• Carbohydrates → 4 kcal per gram
• Protein → 4 kcal per gram
• Fat → 9 kcal per gram
• Alcohol → 7 kcal per gram

In practice, though, you don't need to know the macros by heart: just start from the calories per 100 g of the food (found on the label or in nutrition tables) and scale it to the actual weight.

How to Calculate the Calories in a Food

Calculating a single food is a simple proportion:

Example: chicken breast has about 165 kcal per 100 g. If you eat 200 g: (165 × 200) ÷ 100 = 330 kcal. The same logic applies to any food: you just need the value per 100 g and a scale.

How to Calculate the Calories in a Meal

A meal is simply the sum of its foods. Here's how:

• Weigh each food on the plate (raw, when possible).
• Find the kcal per 100 g for each one (label or reference table).
• Calculate the calories for each food using the proportion above.
• Add up all the values.

How to Calculate the Calories in a Recipe (Step-by-Step Example)

For a recipe, the method is the same, but at the end you divide by the number of servings to get the calories per portion. Let's use a tomato pasta (1 serving):

• Dry pasta — 80 g × 350 kcal/100g = 280 kcal
• Tomato passata — 100 g × 30 kcal/100g = 30 kcal
• Olive oil — 10 g × 884 kcal/100g = 88 kcal
• Parmesan — 10 g × 392 kcal/100g = 39 kcal
• Total: about 437 kcal

If the same recipe served 2, you'd divide the total by 2 → about 218 kcal per serving. Simple: add up the ingredients, then divide by the number of servings.

The Fastest Manual Method: Use a Reference Table

So you don't have to recalculate from scratch every time, keep the calories per 100 g of the foods you eat most often on hand. Here are the values for the most common foods:

Calorie Table for Common Foods (per 100 g)

• Chicken breast — 165 kcal
• Dry pasta — 350 kcal
• Rice (dry) — 350 kcal
• Bread — 265 kcal
• Potatoes — 77 kcal
• Egg (whole) — 155 kcal
• Tuna in water — 116 kcal
• Salmon — 208 kcal
• Mozzarella — 250 kcal
• Parmesan — 392 kcal
• Whole milk — 64 kcal
• Greek yogurt — 90 kcal
• Olive oil — 884 kcal
• Apple — 52 kcal
• Banana — 89 kcal
• Lentils (cooked) — 116 kcal

The Easiest Way: Calculate Calories with Leana

Doing all the math by hand works, but it's slow. Leana is a free app that lets you calculate the calories in what you eat in just a few clicks: search for the food, enter the quantity, and instantly get calories and macros (protein, carbs, and fat).

And if you're feeling lazier, you can also snap a photo of your plate: the AI recognizes the foods and estimates the calories for you in seconds.