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. Fiber comes from 14 grams per 1,000 calories multiplied by the label’s 2,000-calorie reference. Protein comes from assigning 10% of those calories to protein, then dividing by 4 calories per gram.
The cereal aisle is less helpful. One box says “20% Daily Value” and expects you to know whether that’s impressive. I used to read %DV like a score from Washington. It’s just arithmetic in a government-approved outfit.
| 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 behind the %DV column. If a serving lists 10% DV, it supplies one tenth of the label’s reference amount for that nutrient. That’s it. No tiny FDA official is nodding behind the package.
It isn’t personal. FDA uses one 2,000-calorie reference to keep packages consistent, even though people don’t all eat the same amount. It’s the same ruler on every box. That ruler can compare cereals. It doesn’t know you ate dinner over the sink last night.
The current FDA Daily Value reference lists 28g for fiber and 50g for protein. They anchor our fiber budget guide and protein budget guide. Cost comparisons need one finish line. Otherwise, every product brings its own ruler and marketing wins.
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 it 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 replaced the older 25g value. The useful part here is the common denominator. A can of beans and a box of cereal can be compared without each manufacturer inventing a flattering definition of “a lot.”
A pot of split pea soup and savory oatmeal bowls use the low-cost staples that lead our fiber data. Neither recipe has to land on exactly 28g like it’s parking in a narrow garage. They show the label math 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 value in 2016 and kept it at 50g. The number fit the percentage range the agency reviewed and worked as a general label reference. Again, label reference. It isn’t generated after the eggs interview you about your lifestyle.
Beans and rice can spread protein across an inexpensive batch, while high-protein vegetarian breakfast burritos turn similar ingredients into freezer food. They aren’t legal definitions. They’re a better 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%.
In other words, “good source” isn’t the copywriter feeling optimistic on a Tuesday. It has a numerical gate.
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 company puts a protein %DV on the package, FDA rules can make it adjust the amount for protein quality first. 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 numbers without asking you to become a regulatory attorney before breakfast.
How do our four cost studies use these targets?
Our studies use FDA numbers as measuring sticks, not personal instructions. A spreadsheet loves a fixed target and knows nothing about you.
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, and nobody wants a dinner assembled by the lowest cell in column G.
The 30-gram fiber day study uses a round target just above 28g. The 50-gram protein day study uses the FDA value directly. Our methodology page covers the unglamorous parts where receipts and serving sizes refuse to line up.
One reference system lets all four projects speak the same language. Without it, “cheap protein” and “cheap fiber” are just opinions holding a calculator.
What should you do with the numbers?
Use 28g and 50g to read labels, compare prices, and understand our data. They aren’t daily pass-or-fail tests. FDA built them for consistent labeling, which is why they work for cost analysis.
At the store, look at four things together: the gram amount, the %DV, the serving size, and the price. The front of the box tells you the legal bucket the product reached, usually in the largest type it could negotiate. The Nutrition Facts panel gives you the amount. The shelf tag tells you what that claim costs.
That’s the useful version of 28g and 50g. Two standardized numbers, one quick comparison, and far less time standing in the cereal aisle pretending the side of the box is perfectly clear.
