Guides · Updated · 8 min read

How to calculate nutrition for a homemade recipe, per serving

How to work out calories, protein, carbs and fat for a homemade recipe by hand, where the numbers go wrong and how to use them to cook better without tracking every meal.

A sandwich with omelette, carrot and lettuce, halved on a plate with salad, on a wooden tray.
Hands stir sliced banana and oats in a light green pan.
Measuring cups and spoons lie on a white surface with butter, eggs, a whisk and a bowl of oats.

A nutrition label for a home recipe is arithmetic: add up the ingredients, divide by the servings. The sum is easy. The error is in the inputs: how you measured, what the heat did and how big a serving really was.

The method

  1. List every ingredient with its amount

    Weigh in grams where you can. Include the oil in the pan and the butter on top.

  2. Look each one up

    USDA FoodData Central is free and lists calories, protein, carbohydrates, fat, fiber, sugars and sodium per 100 grams. Choose the entry that matches what you weighed: raw chicken thigh, dry rice, whole milk.

  3. Scale each one

    Multiply the per-100-gram values by the grams you used, divided by 100.

  4. Add them up

    That is the whole recipe.

  5. Divide by servings

    That is one serving, if the servings are equal.
A container of flour sits on a black digital kitchen scale that reads 125.2 with flour dust on the surface.

A kitchen scale is the one tool that matters here. Grams are the unit the database uses, so weighing skips every conversion.

A worked example

Overnight oats for two, with values from USDA FoodData Central, rounded. The whole recipe comes to about 560 calories and 20 g protein, so one of two servings is about 280 calories and 10 g protein. Change the servings to see the split.

Overnight oats, worked out

  • 80 g rolled oats300 kcal · 10.5 g protein
  • 250 ml whole milk157 kcal · 8 g protein
  • 1 medium banana105 kcal · 1.3 g protein

Whole recipe: about 560 kcal and 20 g protein.

Split into

280

kcal per serving

10

g protein per serving

Where the numbers go wrong

what one cup of flour weighs, depending on the scoop
120–150 g
what one cup of flour weighs, depending on the scoop
how much rice gains in weight as it cooks
3×
how much rice gains in weight as it cooks
the swing in a recipe that measures flour in cups
25%
the swing in a recipe that measures flour in cups

  • Cups instead of grams

    A cup of flour weighs anywhere from about 120 to 150 grams depending on how it is scooped. That is a 25 percent swing before anything is cooked.

  • Raw and cooked mixed up

    Rice roughly triples in weight as it cooks. Weighing dry rice and using the cooked rice entry undercounts it by about two thirds.

  • Oil left in the pan

    If a tablespoon of oil is left behind after frying, it was not eaten. If the recipe is deep-fried, the absorbed oil is the hard part to estimate.

  • “Salt to taste”

    Sodium is the number most home estimates miss, because salt is added by feel. Measure it once to see what “to taste” means in your kitchen.

  • Uneven servings

    “Serves 4” is a plan, not a measurement. If the portions go out uneven, so do the numbers.

Weigh the finished pot

  1. Weigh the empty pot

    Before you start cooking.

  2. Weigh it full when it is done

    The difference is the weight of the dish.

  3. Divide the totals by that weight

    That gives values per gram.

  4. Multiply by the weight of your bowl

    That is your serving, however big it was.

It works for soups, stews, curries and anything served by the ladle. It deals with uneven servings and with water that cooked off, in one step.

What the numbers are for

You do not need to track every meal to use nutrition numbers. Working them out once for the recipes you cook most shows where your week comes from. Three numbers per serving are the most useful to compare:

protein a day, the US Daily Value. It keeps a meal filling.
50 g
protein a day, the US Daily Value. It keeps a meal filling.
fiber a day, the Daily Value. Most people eat too little.
28 g
fiber a day, the Daily Value. Most people eat too little.
sodium a day, the Daily Value. Most people eat too much.
<2,300 mg
sodium a day, the Daily Value. Most people eat too much.

Daily Values are set for a 2,000-calorie day and are a reference, not a target for everyone. If you are following a diet for a medical reason, work it out with a registered dietitian.

Change the recipes you already cook

A white bowl holds rice, roasted sweet potato, kale, tomato and white beans topped with green sauce.

Eating better at home is usually a set of small changes to dishes you already like, not a new set of recipes. Change one thing at a time and work the numbers out again.

Skip

  • A new diet and a new set of recipes
  • Oil poured straight from the bottle
  • Salt added until it tastes right

Do

  • Add a can of beans or lentils to a soup, chili or pasta sauce
  • Double the vegetables and cut the pasta or rice by a quarter
  • Measure the oil
  • Cut the salt by a third and finish with lemon or vinegar

Keep the changed recipe as a version next to the original, with a note of what you changed. If the family prefers the original on Fridays, both are there.

Where Forktales fits

Forktales can estimate nutrition for a recipe in your recipe box. From the ingredients and servings it works out calories, protein, carbs, fat, fiber, sugars and sodium for one serving, with a note on the biggest assumption it made, labelled as an estimate. It spends one credit. When the author changes the ingredients or servings and has a credit left, the estimate is worked out again and spends that credit. Forktales does not log what you eat or add up your day.

Questions

How do I calculate calories in a homemade recipe?

Weigh each ingredient, look up its calories per 100 grams in a food database such as USDA FoodData Central, multiply by the grams you used divided by 100, add up the ingredients and divide the total by the number of servings.

Should I use raw or cooked weights?

Use the weight of each ingredient as it went into the pot, which is usually raw or dry, and look up the raw or dry entry in the database. Cooking changes the weight through water and fat, not the nutrients you put in.

How do I work out calories per serving for soup or stew?

Weigh the empty pot, then weigh it again full once cooked. The difference is the weight of the dish. Divide the recipe's total calories by that weight to get calories per gram, then multiply by the weight of your bowl.

How accurate are recipe nutrition calculators?

They are as accurate as what you enter. Weighed raw ingredients and the right database entries give a close estimate. Cups of flour, oil left in the pan and servings that are really uneven all add error. Treat the result as an estimate, not a label.

Can Forktales track what I eat?

No. Forktales estimates nutrition for one serving of a recipe from its ingredients and servings. It does not log meals or add up a day.

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