Calorie Portion Calculator

How much food is 150 Calories? Enter the serving size and Calories from the nutrition label along with your calorie target, and this calculator tells you exactly how much to eat in grams, ounces, cups, tablespoons, or teaspoons. You can also work in reverse: enter how much you plan to eat and find out how many Calories it contains. No food database or searching is required. It works with virtually any packaged food.

Enter the Calories per serving from the nutrition label.

This calorie portion calculator works out how much of a food fits a calorie target, or how many Calories are in the amount you are eating, using nothing but the food's nutrition label. There is no food database to search: you copy the Calories and serving size from the package, so the answer is for the exact product in your cupboard. It accepts serving sizes the way labels print them, including fractions such as 3/4 cup or 1 1/2 tbsp, and gives the result in grams, ounces, cups, tablespoons, teaspoons, milliliters, pieces, slices, and servings.

How to Use the Calorie Portion Calculator

Under From the nutrition label, copy three things from the package:

Calories per serving, the large number on the label.
The serving size and its unit, such as 3/4 cup, 2 tbsp, 1 bar, or 1 slice. Use piece for anything counted that isn't a slice: a cookie, an egg, a bar, or a cracker.
The weight or volume printed in brackets after the serving size, such as (55 g) or (240 mL). This is optional, but without it the calculator can only give the portion in units of the same kind as the serving size.

Then fill in Your calorie target or amount. Type a number of Calories to see how much food that is, or type an amount to see how many Calories it has. Whichever of the two fields you type in last becomes the starting value, and the other updates as you type. The results show the portion in every unit the label allows, and for foods measured by volume, as a combination of standard measuring cups and spoons. Your last entries are saved in your browser, so the label is still there the next time you open the page.

The Formula

The calculation is a simple proportion. To find the amount for a calorie target:

Amount = Target Calories ÷ Calories per serving × Serving size

Suppose a box of cereal says Serving size 3/4 cup (55 g), Calories 210, and you want 150 Calories. That is 150 ÷ 210 = 0.71 servings, which is 0.71 × 55 g = 39 g, or 0.71 × 3/4 cup = 0.54 cup. In measuring cups and spoons, that is about 1/2 cup plus 1 3/4 teaspoons. Going the other way, 1/3 cup of the same cereal is 1/3 ÷ 3/4 = 0.44 servings, or 0.44 × 210 = 93 Calories.

Why the Gram Amount Matters

Cups, tablespoons, and teaspoons measure volume. Grams and ounces measure weight. How much a cup of something weighs depends entirely on the food: a cup of flour weighs about half as much as a cup of sugar, and a cup of puffed rice far less than either. A general-purpose converter can't turn cups into grams without knowing the food's density.

Nutrition labels solve this for you. In the United States, the serving size is given in a household measure followed by its metric equivalent, as in "3/4 cup (55 g)" or "2 tbsp (32 g)". That pairing is the food's density, measured by the manufacturer. Enter both numbers and the calculator can move freely between weight and volume for that food. Leave the metric amount out and it only converts within the kind of unit you gave: cups to tablespoons, teaspoons, and milliliters, or grams to ounces. Pieces and slices only convert through the label's weight too, since the calculator has no way of knowing how much one piece weighs.

Weighing Versus Measuring

For accuracy, weigh your food. A digital kitchen scale reads to the nearest gram, while cups depend on how the food is packed. A loosely spooned cup and a firmly pressed cup of the same cereal, cheese, or brown sugar can differ by a fifth or more, and the label's gram amount is for a cup filled the manufacturer's way. Measuring cups and spoons are perfectly good for liquids, and for foods where a few Calories either way don't matter to you.

The volume units in this calculator follow the equivalents US labels are printed with: 1 teaspoon is 5 mL, 1 tablespoon is 15 mL, 1 fluid ounce is 30 mL, and 1 cup is 240 mL. Ounces are weight ounces of 28.35 g, which is what a kitchen scale shows. A label's own "1 oz (28 g)" is used as printed, so entering 1 oz gives exactly 1 serving.

Raw, Dry, and Cooked Weights

Label weights are for the food as it comes out of the package. For pasta, rice, oats, lentils, and raw meat, that means the dry or raw weight, not the cooked weight. Dry pasta roughly doubles to triples in weight as it cooks, while meat loses water and gets lighter. Weighing cooked pasta against a dry-pasta label can overstate the Calories two or three times over.

The simplest fix is to weigh these foods before cooking. If you cook a batch, weigh it raw and again cooked, divide the cooked weight by the raw weight, and multiply the gram amount the calculator gives you by that ratio to get the cooked portion to serve.

European and Other Labels

Labels in the European Union and the UK give nutrition per 100 g, or per 100 mL for drinks, and often per portion as well. Either works: enter the kcal figure as the Calories and 100 g as the serving size. If a label gives energy only in kilojoules, divide by 4.184 to get Calories, or use the food energy converter on the Measurement Conversions page. Australian and New Zealand labels give both a per-serving and a per-100 g column, so you can use whichever is easier.

How Accurate Is the Result?

The arithmetic is exact, so the result is as accurate as the label. Labels are rounded: US labels round Calories to the nearest 5 up to 50 and to the nearest 10 above that, and the serving size is often rounded to a convenient household measure. Labels are also allowed some leeway. The FDA treats a food as mislabeled only when it contains more than 20% more Calories than stated, and one study found supermarket frozen meals averaged 8% more Calories than their labels, and restaurant foods 18% more.

To keep the numbers honest, the calculator rounds grams and milliliters to whole numbers (one decimal below 10), cups and ounces to two decimals, and spoons to one. Its measuring-cup combination uses the nearest quarter teaspoon and says "about" when it isn't exact. For day-to-day calorie tracking, that is more precision than the label itself carries.

Putting Your Calorie Target to Work

The calculator answers the question other calorie calculators leave open: once you know your target, how much food is that? Use the TDEE Calculator for All Ages or the Maximum Fat Loss Calculator to set a daily calorie target, split it across meals and snacks, and then use this calculator to portion each food. A 200-Calorie snack of nuts, a 350-Calorie bowl of cereal with milk, or a 100-Calorie serving of crackers all become concrete amounts you can weigh or measure.

Frequently Asked Questions about Calorie Portions

How do I work out how many grams of a food are in a given number of Calories?

Divide the Calories you want by the Calories per serving on the label, then multiply by the serving size in grams. For a cereal labeled 210 Calories per 3/4 cup (55 g), 150 Calories is 150 ÷ 210 × 55 = 39.3 g. The calculator does the same sum and also gives the result in cups, tablespoons, and any other unit the label lets it convert to.

Why can't the calculator convert cups to grams for every food?

Cups measure volume and grams measure weight, and how much a cup weighs depends on the food: a cup of flour weighs about half as much as a cup of sugar. The only reliable link between the two for a particular food is the label itself, which usually prints both, as in "3/4 cup (55 g)". Enter the gram amount from the label and the calculator can convert between the two; leave it out and it sticks to units it can convert safely.

Should I weigh or measure my food?

Weigh it when you can. A kitchen scale reads grams to within a gram or two, while a cup of cereal or shredded cheese can vary by 20% or more depending on how it is packed. Cups and spoons are fine for liquids and for foods where a small difference doesn't matter to you.

Does the label weight apply to cooked food?

Usually not. Label weights are for the food as sold, so for pasta, rice, oats, and raw meat they are the dry or raw weight. Cooking changes the weight a lot: pasta roughly doubles or triples as it absorbs water, while meat loses water and shrinks. Weigh these foods before cooking, or divide the cooked weight by the cooked-to-raw ratio for your batch.

How accurate are the Calories on a nutrition label?

Reasonably, but not exactly. In the US, Calories are rounded to the nearest 5 up to 50 and to the nearest 10 above that, and the FDA treats a food as mislabeled only when it contains more than 20% more Calories than stated. A 2010 study found packaged frozen meals averaged 8% more Calories than their labels, and restaurant foods 18% more. Treat the result as a close estimate rather than an exact count.

Can I use a European label that gives energy per 100 g?

Yes. Enter the kcal figure as the Calories, and 100 g (or 100 mL for drinks) as the serving. If the label lists energy only in kilojoules, divide by 4.184 to get Calories, or use the food energy converter on the Measurement Conversions page.

What does "serving" mean in the results?

One serving is the amount the label's Calories are given for. If the label says 210 Calories per 3/4 cup, then 1 serving is 3/4 cup, and 0.71 servings is 150 Calories. It is not necessarily the amount you normally eat, and it is not a recommendation: US serving sizes are based on the amounts people typically eat at one time.