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Guide

How to calculate serving size for a nutrition label

How to turn a batch into grams per serving, how FDA reference amounts set the serving size for packaged food, and how to write the serving size line on the label.

Updated 2026-09-16. This page is not legal advice.

How do I get grams per serving?

Weigh the whole finished batch. Divide by the number of servings. A sheet of 24 cookies that weighs 720 g after baking gives 30 g per cookie. Weigh after cooking, not before. Water leaves the food in the oven, so the raw weight is higher than the weight the customer gets.

The Serving Size Calculator does this division, converts to ounces, and divides your batch totals for calories and nutrients by the number of servings with FDA rounding.

Who chooses the number of servings?

For a packaged food sold at retail, FDA does. The rule in 21 CFR 101.9(b) says the serving size must come from the Reference Amount Customarily Consumed, or RACC, for the food category. The reference amounts are listed in 21 CFR 101.12(b). A few that small makers use often, read from the eCFR on 2026-09-16:

Food Reference amount
Cookies 30 g
Brownies 40 g
Bread and rolls 50 g
Muffins, bagels 110 g
Doughnuts, sweet rolls, coffee cake, sweet quick breads 55 g
Cake, medium weight (leavened cake with or without icing, cupcakes) 80 g
Cake, heavyweight (cheesecake, fruit cake) 125 g
Cake, light weight (angel food, sponge, no icing) 55 g
Pies, cobblers, fruit crisps, turnovers 125 g
Granola bars and other grain-based bars 40 g
Hard candies 15 g
All other candies (fudge, caramels, chocolates) 30 g
Nuts, seeds, and mixes 30 g
Honey, jams, jellies, fruit butter 1 tbsp

If your small business is exempt from nutrition labeling, none of this binds you. Read do cottage foods need a Nutrition Facts label for the exemption. If you print a panel anyway, use the reference amount. A buyer who compares your cookie with a store cookie expects the same serving.

How does the reference amount become a serving size?

For food in pieces, such as cookies, muffins, and slices, 21 CFR 101.9(b)(2)(i) gives four cases. Weigh one piece and compare it with the reference amount.

  • One piece weighs 50 percent or less of the reference amount: the serving is the number of whole pieces closest to the reference amount. A 12 g cookie against 30 g gives 3 cookies (36g).
  • One piece weighs more than 50 percent but less than 67 percent: you may declare one piece or two. An 18 g cookie can be 1 cookie (18g) or 2 cookies (36g).
  • One piece weighs 67 percent or more but less than 200 percent: the serving is one piece. A 45 g cookie is 1 cookie (45g).
  • One piece weighs 200 percent to 300 percent: the serving is the amount that approximates the reference amount, and the label must add a second column with the values for the whole piece. A 75 g cookie needs both.

For food you scoop or pour, such as granola, candy, or jam, the serving is the household measure that comes closest to the reference amount. Measure a level 1/4 cup, 1/3 cup, 1/2 cup, or 1 cup of the food and weigh it. Pick the measure whose weight is closest to the reference amount.

What about a single package?

A package that holds less than 200 percent of the reference amount is one serving. The whole package is the serving size, whatever it weighs. A 55 g bag of granola bites, against a 40 g reference amount, is one serving of 55 g. A package that holds 200 percent to 300 percent needs the dual-column label with per-serving and per-package values.

How do I write the serving size line?

Household measure first, then the metric weight in parentheses: “2 cookies (32g)”, “1 muffin (95g)”, “1/4 cup (30g)”. Round the gram figure to the nearest whole gram. Between 2 g and 5 g, round to the nearest 0.5 g. Under 2 g, use 0.1 g steps. You may add ounces after the grams. The line goes directly under “servings per container”, in larger bold type than the nutrient lines.

What can go wrong?

  • Weighing the raw batch. Baked goods lose water in the oven, so the label overstates the serving.
  • Rounding the serving to a nice number. The gram figure comes from the scale, not from a wish.
  • Counting servings per container from the recipe yield instead of the package. If the recipe makes 24 cookies and you sell bags of 6, the container has 3 servings of 2 cookies.
  • Using a cup measure for a dense food without weighing it. Two people fill a cup differently. The gram figure in parentheses is the one that binds you.

Once you have grams per serving, the Serving Size Calculator gives the per-serving nutrients from your batch totals, and the Nutrition Label Maker prints the panel.

Frequently asked questions

How do I calculate serving size from a recipe?

Weigh the finished batch in grams after cooking. Divide by the number of servings. That is the grams per serving. The Serving Size Calculator does the division and the FDA rounding.

Can I pick any serving size I want?

Not for packaged food sold at retail. FDA sets a reference amount for each food category in 21 CFR 101.12, and the serving size must be based on it. If your small business is exempt from nutrition labeling, the serving size is your choice, but keep it honest.

What is the serving size for cookies?

The FDA reference amount for cookies is 30 g. If one cookie weighs 30 g, the serving is 1 cookie (30g). If one cookie weighs 12 g, the serving is 3 cookies (36g), because three is the number closest to 30 g.

How do I write the serving size line?

A household measure first, then the metric weight in parentheses. For example "2 cookies (32g)" or "1/4 cup (30g)". The gram figure rounds to the nearest whole gram.

Is a whole muffin one serving?

For a retail label, a unit that weighs 67 percent or more of the reference amount is one serving. The muffin reference amount is 110 g, so any muffin of 74 g or more is one serving.