The FDA’s food-label reference numbers are 28 grams of fiber and 50 grams of protein for adults and children age 4 or older. The fiber number comes from 14 grams per 1,000 calories multiplied by the label’s 2,000-calorie reference. The protein number comes from assigning 10% of those calories to protein, then dividing by 4 calories per gram.
| Label number | Official basis |
|---|---|
| Fiber Daily Value: 28g | 14g per 1,000 calories × 2,000 calories |
| Protein Daily Value: 50g | 10% of 2,000 calories ÷ 4 calories per gram |
| ”Good source” | 10% to 19% of the Daily Value |
| ”High” or “excellent source” | 20% or more of the Daily Value |
Source: FDA, 21 CFR 101.9 and 101.54; FDA, “Food Labeling: Revision of the Nutrition and Supplement Facts Labels,” 81 FR 33742, May 27, 2016.
What is a Daily Value?
A Daily Value is the reference number behind the %DV column on a Nutrition Facts label. If a serving lists 10% DV, the package is saying that serving supplies one tenth of the label’s daily reference amount for that nutrient. That’s it. The number helps you compare products that otherwise arrive wrapped in adjectives.
It isn’t a personal prescription. FDA uses one 2,000-calorie reference to keep the math consistent across packages, even though people don’t all eat the same amount. Think of it as the ruler printed on every box. A ruler can compare two cereals without knowing anything about the person holding them.
The current FDA Daily Value reference lists 28g for dietary fiber and 50g for protein. Those are also the anchors behind our fiber budget guide and protein budget guide, because cost comparisons need a fixed finish line.
Where does 28 grams of fiber come from?
FDA explained the 28g fiber Daily Value in its 2016 Nutrition Facts final rule. The agency used the Institute of Medicine’s reference of 14 grams per 1,000 calories. Multiply that by the label’s 2,000-calorie reference and you get 28 grams.
The arithmetic is almost suspiciously tidy:
14g per 1,000 calories × 2 = 28g.
That number replaced the older 25g label value. We’re not turning the agency’s evidence discussion into a health claim here. The useful economics point is simpler: 28g became the common denominator on packages, so a can of beans and a box of cereal can be compared using the same reference.
Food makes the number less abstract. A pot of split pea soup and a batch of savory oatmeal bowls use the same low-cost staples that lead our fiber price data. You don’t need either recipe to land on exactly 28g. They just show what the label math looks like after it leaves the box.
Where does 50 grams of protein come from?
The protein Daily Value starts with 10% of the 2,000-calorie reference. Ten percent is 200 calories. Protein supplies 4 calories per gram, so 200 divided by 4 equals 50 grams.
2,000 calories × 10% ÷ 4 calories per gram = 50g.
FDA considered changing the protein value during the 2016 label revision and kept it at 50g. The agency said the value fell within the accepted percentage range it reviewed and worked as a general labeling reference. Again, label reference. Not a bespoke number generated by your grocery cart.
This is where familiar food earns its keep. Beans and rice can spread protein across a cheap batch, while high-protein vegetarian breakfast burritos turn the same kind of ingredients into freezer food. The recipes aren’t legal definitions. They’re just a much more useful picture than a lonely 50 on a label.
What does good source legally mean?
This part isn’t marketing improv. Under the current text of 21 CFR 101.54, “good source,” “contains,” and “provides” generally require 10% to 19% of the Daily Value per reference amount customarily consumed. “High,” “rich in,” and “excellent source of” start at 20%.
For fiber, the conversion is clean:
| Package language | Percent Daily Value | Fiber amount based on 28g DV |
|---|---|---|
| FDA’s general low guide | 5% or less | 1.4g or less |
| Good source | 10% to 19% | 2.8g to about 5.3g |
| High or excellent source | 20% or more | 5.6g or more |
Source: FDA, 21 CFR 101.54 and “The Lows and Highs of Percent Daily Value on the Nutrition Facts Label.”
Protein labels have an extra wrinkle: when a protein %DV is calculated, FDA rules can require the amount to be adjusted for protein quality. That means “5g of protein equals 10%” isn’t a safe legal shortcut for every product. For the full fiber version, our guide to what “good source of fiber” means walks through the cereal-aisle math without asking you to become a regulatory attorney before breakfast.
How do our four cost studies use these targets?
Our studies use the FDA numbers as measuring sticks, not as personalized instructions.
The fiber-per-dollar ranking asks how many grams of fiber one dollar buys across common foods. The protein-per-dollar ranking does the same for protein. Neither ranking says the cheapest food should become your entire menu. That would be spreadsheet cosplay.
The two daily-cost studies make the reference numbers more concrete. The 30-gram fiber day study uses a round search-friendly target slightly above the 28g Daily Value. The 50-gram protein day study uses the FDA value directly. Our methodology page explains how the nutrition data and dated prices are handled.
One reference system lets all four projects speak the same language. Without it, “cheap protein” and “cheap fiber” are just opinions wearing a calculator.
What should you do with the numbers?
Use 28g and 50g to read labels, compare prices, and understand our datasets. They aren’t two daily tests you either pass or fail. The FDA built them for consistent labeling, which is why they work so well for cost analysis.
At the store, compare the gram amount, the %DV, the serving size, and the price together. A front-of-box claim tells you which legal bucket the product reached. The Nutrition Facts panel tells you the amount. The shelf tag tells you what the claim costs. That’s the whole system, and it fits in one glance once you know what the two numbers are doing there.
