Label practice
How to compare two food labels on the same amount of food.
One box prints 18 grams of carbohydrate, the box beside it prints 20, and the first looks smaller. Each number describes its own serving, though. Here is how to put both labels on the same weight of food, in five short steps you can check with a pencil.
Every value on this page is fictional and labeled as such.
You are standing in the aisle with a box that prints 18 grams of carbohydrate, trying to work out whether that is one serving or the whole box. If it is one serving, the box is a different number entirely. Either way the snack turns into a guilt trip before you reach the checkout.
Two similar foods often print their numbers on different amounts of food. In the fictional pair below, one label describes 30 grams and the other 40 grams, so the number that looks smaller may simply describe a smaller serving. This page puts both labels on the same basis, with the arithmetic written out in full. It takes about five minutes with a pencil, and nothing here tells you what to eat or how much.
The serving size is not a recommendation.
Label serving sizes are standardized to make similar foods easier to compare. A serving size is written in a familiar unit first, such as cups or pieces, then as a metric amount in grams. The FDA says plainly that the serving size reflects the amount people typically eat or drink, and that it is not a recommendation of how much you should eat or drink.
Standardized does not mean identical. Two products can land on different serving weights, which is why the fictional pair below prints its numbers on 30 grams and 40 grams. Set those two numbers side by side without adjusting them and they invite the wrong conclusion.
The FDA’s guide to the Nutrition Facts label says to make sure the serving size is the same when you compare two foods. Its serving size page explains where the household measure and the grams come from. Neither number is a target.
If grams and cups still feel slippery, read how label numbers start with the units first. The comparison below is easier once the units are clear.
The same-basis method, in five steps.
Same basis means both numbers describe the same weight of the same kind of food.
1. Match the state of the food.
Labels describe food as packaged. Compare dry with dry, cooked with cooked, drained with drained.
2. Read the per-serving column on both labels.
Write down each label’s serving weight in grams. This is the step people skip, because the serving weight sits in small type above the large number.
3. Copy the same line, exactly as printed.
The FDA label guide lists Total Carbohydrate in grams, with dietary fiber and total sugars indented underneath it. Copy the Total Carbohydrate number and stop there. Do not subtract anything from it.
4. Choose one common weight of food.
Every comparison needs one shared number, or the two results cannot be read side by side.
5. Divide for the factor, then multiply for the result.
Factor = common grams ÷ that food’s serving grams. Result = printed grams × factor. Do this separately for each food, then compare the two results, not the printed numbers.
A fictional label pair, worked out.
| Step | Food A | Food B |
|---|---|---|
| Serving weight, as printed | 30 g | 40 g |
| Total Carbohydrate per serving, as printed | 18 g | 20 g |
| Common weight for the comparison | 60 g | 60 g |
| Factor: common weight ÷ serving weight | 60 ÷ 30 = 2 | 60 ÷ 40 = 1.5 |
| Result: printed grams × factor | 18 × 2 = 36 g | 20 × 1.5 = 30 g |
Food A: 18 × (60 ÷ 30) = 36 g · Food B: 20 × (60 ÷ 40) = 30 g
Illustrative values only, invented for arithmetic practice. Not a recommended serving, food choice or target.
Read that again, because it is the point of the page. Food A printed the smaller number, 18 g. On the same 60 g of food, Food A gives the larger figure. The printed numbers were never comparable, because each one described a different serving weight. None of this says either food is better, or that 60 g is a sensible amount of anything. It only shows what the two labels say on one scale.
The per-package column answers a different question.
Some labels also print a number for the whole package. That number answers a question about the package in your hand: what is inside all of it. It is not a like-for-like comparison when two packages hold different amounts. Two slips follow from mixing the columns: multiplying a package total by the serving count a second time, which makes a food look bigger than it is, or setting one product’s package total beside another product’s per-serving number. Keep the questions apart. If the serving-count lines are the part that confuses you, the walk-through of servings per container takes them one at a time.
One line cannot tell you whether a food suits you.
Total Carbohydrate is one line on a panel that also lists fiber, added sugars, sodium and protein. What you eat alongside a food, your medicines and your history all sit outside the label. A comparison like the one above shows how two labels line up on one line at one weight. It cannot tell you which food to buy or how much to eat.
What it can do is turn a vague worry into a written question. For the fictional pair: “On the same 60 grams of each, the label arithmetic gives 36 grams and 30 grams. Does a difference that size matter for me?” That belongs with your care team, who know the parts a label does not print. The free Care-Team Conversation Planner has space for three written questions and the answer you are given; the question builder runs in your browser, and the printable PDF arrives by email after you reply VERIFY.
Why this is label practice, not a promise.
You may have come here looking for something to take or to do, and found arithmetic instead. That is a fair objection.
This site publishes education. It does not diagnose, it does not treat, it does not recommend a supplement, and it does not set a target for you. That caution is not fussiness. The FDA keeps a page on illegally sold diabetes treatments because products that promise to end diabetes do appear for sale. NCCIH’s summary of the evidence on dietary supplements reports that in a 2022 review of vitamins, the improvements seen with vitamin D were small and of low certainty, and the authors concluded that the available evidence supports current recommendations that nutritional supplements may not be helpful for blood glucose control.
And because free health pages so often turn into a sales pitch: the method, the five steps and the worked example are complete on this page. Our Editorial Policy explains how pages are sourced and updated, and Review Methodology explains what a review would involve. Nobody has clinically reviewed this page yet, and the bar at the top says so instead of implying otherwise.
Practice on one label, then draw your own table.
Practicing one label first is enough to see the per-serving and per-package lines in action. The free food-label practice tool runs in your browser and walks through a single fictional label.
For the comparison itself, the free Food Label Comparison Workbook is the printable version of this method: a six-page workbook and a one-page comparison sheet, both free, sent by email after you reply VERIFY. Or copy this table onto the back of an envelope and fill it in with two packages you already have at home. You do not have to change what you eat; reading the two labels is the whole exercise.
| Step | Your food 1 | Your food 2 |
|---|---|---|
| Serving weight in grams, as printed | write the grams | write the grams |
| Total Carbohydrate per serving, as printed | write the grams | write the grams |
| Common weight you chose | write the grams | write the grams |
| Result: printed × (common ÷ serving) | write the result | write the result |
A blank practice table for your own two labels. It is not a food record, and nobody sees it but you.
Keep the numbers in one place, with the words beside them: “36 g, per 60 g of food.” A number without its basis is the one that misleads you next week.
Common questions about comparing labels.
Why can’t I just compare the two carbohydrate numbers?
Because they may describe different amounts of food. A smaller printed number can belong to a smaller serving weight. Put both labels on one common weight first: factor = common grams ÷ that food’s serving grams, then result = printed grams × factor.
Should I use the per-package column instead?
A per-package number answers a different question: what is inside the package you are holding. It is not a like-for-like comparison when two packages hold different amounts. Use the per-serving column plus one common weight for a comparison, and the per-package number for the package itself.
Does this method tell me which food is better for me?
No. It shows how two labels line up on one line at one weight. Whether a food suits you depends on things a label does not print, so that question belongs with your care team.
General education only. This page helps you organize learning and questions. It is not medical advice and does not recommend a treatment, diet, medicine or blood-sugar target. Personal health decisions belong with your care team. Medical and educational disclaimer
Sources and editorial notes
- US Food and Drug Administration, Serving Size on the Nutrition Facts Label, retrieved October 18, 2026.
- US Food and Drug Administration, How to Understand and Use the Nutrition Facts Label, retrieved October 18, 2026.
- US Food and Drug Administration, Illegally Sold Diabetes Treatments, retrieved October 18, 2026.
- National Center for Complementary and Integrative Health, Diabetes and Dietary Supplements: What You Need to Know, retrieved October 18, 2026.
Food A and Food B are fictional practice labels. Every value in the worked example, and the eighteen grams in the opening paragraph, were invented to keep the arithmetic simple. Not yet reviewed by a clinician. See our Editorial Policy, Review Methodology and Affiliate Disclosure.
Keep the comparison honest.
Three next reads for the units, the serving math and one-label practice.
Food-Label Numbers Start With the Units
Weight, volume and serving information on a label.
Serving Size of Carbs vs the Whole Package
See whether a number is per serving or per package.
Food-Label Practice
Five fictional labels with explained answers. Runs in your browser.
Start with one useful question.
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