Medical Disclaimer: This calculator provides a general estimate based on established research and is for educational purposes only, not a substitute for medical advice. Individual results can vary based on health conditions, so consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, exercise, or health routine. Read our full Medical Disclaimer.
How Recipe Calories Are Calculated
Recipe calories are the total food energy in everything that goes into a dish, added up one ingredient at a time. Food databases list nutrients per 100 g, so each ingredient is turned into grams, scaled, and added to the total². The total is then divided by your servings or by the weight of the finished dish.
What the Recipe Calorie Estimate Measures
The result estimates the calories, protein, fat, carbohydrate, fiber and sugars in the food you cooked. It does not tell you how much to eat or whether a dish is healthy. It counts only what you enter.
The Formula
Ingredient calories = calories per 100 g x grams used / 100
Recipe calories = the sum of all ingredient calories
Calories per serving = recipe calories / number of servings
Calories per 100 g = recipe calories / cooked weight in grams x 100
The same per-100 g scaling is how USDA tells users to work with its data². The calorie values come from the Atwater system, which converts grams of protein, fat and carbohydrate into energy using general factors of 4, 9 and 4 kcal per gram or factors specific to each food³.
How This Calculator Computes Your Result
Search for each ingredient in our copy of USDA FoodData Central, the US government's public food composition database¹: basic foods (Foundation Foods and SR Legacy) and prepared and mixed foods (FNDDS). Enter the amount by weight (g, kg, oz or lb) or as a household measure such as 1 cup, 1 tbsp or 1 large egg. Household measures use USDA's own gram weight for that food. Missing cup or spoon sizes are worked out from the ones USDA lists (1 cup = 16 tbsp = 48 tsp). If USDA lists none for a food, the tool asks you to weigh it rather than guess. You can also add a custom ingredient from a food label.
Enter the number of servings and, if you can, the weight of the finished dish. Results are rounded only for display: calories to whole numbers, grams to one decimal. An optional label-style view rounds each serving like a US Nutrition Facts label, for example calories above 50 to the nearest 10⁶.
What Your Result Means
Result | What it tells you | When to use it |
Whole recipe | Calories and macros in everything you cooked | Batch cooking, meal prep |
Per serving | The whole recipe divided by your servings | Equal portions, such as a tray cut into 8 |
Per 100 g | Calories and macros in 100 g of the finished dish | Uneven portions: weigh your plate and scale |
Ingredient breakdown | Each ingredient's calories and share of the total | Finding where the calories come from |
Calorie split | Rough share of calories from protein, fat and carbs | Comparing recipes |
Per serving is only right if the portions are equal. Otherwise, weigh your plate and use the per 100 g figure. A 300 g plate of a dish with 105 kcal per 100 g has about 315 kcal. If you leave the cooked weight blank, per 100 g is based on the raw ingredients, and the result says so.
How to Measure Correctly
Use a kitchen scale and grams where you can. USDA lists a cup of all-purpose flour at 125 g¹, but how you fill the cup changes what is in it.
Weigh each ingredient in the state that matches the food you pick: dry pasta with a "dry" entry, raw chicken with a "raw" entry.
For the cooked weight, weigh the empty pot, then the pot with the finished food, and subtract. Do this before anyone takes a serving.
For oil, weigh the bottle before and after cooking and enter the difference.
Count every oil, butter, sauce and topping you add.
Why Raw and Cooked Weights Give Different Numbers
Cooking changes weight much more than it changes calories. Pasta takes up water, so 100 g of dry pasta has 371 kcal in USDA data while 100 g of cooked pasta has 158 kcal¹. Meat loses water instead. In USDA tests, roasted chicken breast kept 72 percent of its raw weight on average, with a range of 61 to 82 percent⁴.
Fat can also leave the food. High-fat ground beef patties (over 22 percent fat) lost fat equal to about 12 percent of their raw weight when grilled or pan-broiled, and low-fat patties lost under 2 percent⁴. This tool assumes everything you enter is eaten, so pouring off fat makes the real number lower than the result.
The most common mistake is mixing states. Entering 200 g of dry pasta with the cooked pasta entry counts 316 kcal instead of 742 kcal¹. This is also why the tool asks for the cooked weight: per 100 g of the finished dish is the number to use when you weigh cooked portions.
Why Every Calorie Count Is an Estimate
The Atwater factors are averages. With the general 4, 9 and 4 factors, 100 g of raw banana works out to about 99 kcal, but USDA's banana-specific factors give 89 kcal¹ ³. Real digestion can differ even more. In a controlled feeding study, almonds provided 129 kcal per 28 g serving, while the Atwater factors predicted 168 to 170 kcal, a 32 percent overestimate⁵.
If you add a custom ingredient from a food label, keep in mind that label numbers are rounded, and US rules treat a food as misbranded only if its calories are more than 20 percent above the label value, so some excess is allowed⁶.
A Note on Accuracy
This calculator is only as accurate as the foods and amounts you enter. USDA values and household measures are averages, and your ingredients will vary. The tool does not estimate oil soaked up in frying or fat lost in cooking. Results are educational estimates, not a lab analysis or a legal nutrition label.
Frequently Asked Questions
How do you calculate calories in a homemade recipe?
Add up the calories of every ingredient from its weight and its calories per 100 g, then divide by the number of servings². Weighing the finished dish also gives calories per 100 g.
Should I weigh food raw or cooked to count calories?
Either works if the food entry matches what you weigh: raw weight with a raw entry, cooked weight with a cooked entry. Dry pasta has 371 kcal per 100 g and cooked pasta has 158, so mixing them up causes large errors¹.
How many calories should a serving be?
There is no single right number for a serving. The Daily Values on US nutrition labels are based on a reference intake of 2,000 calories a day for adults and children aged 4 and older⁶, and the Calorie Calculator can estimate your own needs.
How accurate is a recipe calorie calculator?
It is close enough for meal planning but not exact, because database values are averages and the Atwater factors can be off for some foods, such as almonds by 32 percent⁵. Weighing ingredients in grams and entering the cooked weight gives the most reliable result.
Sources
USDA FoodData Central, USDA Agricultural Research Service
Foundation Foods Documentation, USDA Agricultural Research Service, 2024
Energy Value of Foods: Basis and Derivation, Merrill and Watt, 1955
USDA Table of Cooking Yields for Meat and Poultry, Showell et al., 2012
Measured Versus Predicted Energy of Almonds, Novotny et al., 2012
Nutrition Labeling of Food, 21 CFR 101.9, US Food and Drug Administration