Folate on a Supplement Facts label is declared in mcg DFE, dietary folate equivalents, a unit that counts folic acid as worth more than the folate in food. That is why a tablet with 400 mcg of folic acid can be labeled 680 mcg DFE. This calculator turns a DFE number back into folic acid, converts folic acid into DFE, and builds a label line the way FDA's worked examples do. We built it from FDA's 2019 labeling guidance, the regulation text in 21 CFR 101.9 and FDA's 2016 final rule, then checked it against folate labels as entered in the NIH Dietary Supplement Label Database (DSLD) on October 29, 2026. Brands appear on this page only as label examples.
Before you decide
This page converts units. It does not set an intake, and it does not say whether a product suits you. If a doctor or midwife gave you a folate or folic acid amount, that instruction outranks any number here. This is general information, not medical advice.
The page is for anyone reading the folate line on a Supplement Facts panel: two bottles that print different DFE numbers for the same folic acid, a methylfolate product that prints only a DFE figure, or a prenatal label checked against the Daily Value. Most of the confusion has one source: a DFE number is weighted, so it is larger than the folic acid it stands for.
FDA's rule for the label is short. When folic acid is added to a supplement, the label must declare folate in mcg DFE, the %DV based on mcg DFE, and the folic acid amount by weight in parentheses, according to FDA's 2019 labeling guidance. When that number in parentheses is there, you already have the folic acid amount. The calculator is for the cases where it is missing, or where you want to see how the label got its DFE total.
Convert a folate label
600 mcg DFE is about 353 to 360 mcg of folic acid. Enter any folate line from a Supplement Facts panel below, or switch tabs to start from folic acid or to build a label line from its parts.
Type numbers without commas. A label that says 1.7 mg DFE can be entered as 1.7 with the unit set to mg DFE.
FDA used 1.7 as an example and would not expect a factor above 1.7.
Factors: FDA labeling guidance of August 2019 (mcg DFE = food folate + 1.7 × folic acid) and 21 CFR 101.9 (1 DFE = 0.6 mcg folic acid). Daily Values: 21 CFR 101.9. Upper limit: NIH Office of Dietary Supplements. Results in mcg are rounded to whole numbers. %DV is rounded to the nearest whole percent, the rounding FDA sets for supplements. Links are in Sources and corrections at the end of this page.
This tool converts label units. It does not tell you how much to take. Label-checked, not lab-tested.
Related UsefulVitamins tools and guides
Pick the form the label names first: folic acid has two published conventions, food folate counts one to one, and methylfolate has no official factor. For vitamins A, D and E, which the same FDA guidance covers, use our mcg to IU converter or our vitamin A, E and K converter; other converters are on our tools page.
What mcg DFE means on a Supplement Facts label
DFE stands for dietary folate equivalents. FDA's guidance gives the label formula as mcg DFE = mcg naturally occurring folate + (1.7 × mcg folic acid). The 1.7 comes from absorption: FDA puts folic acid at 85 percent bioavailable and food folate at about 50 percent, and 85 ÷ 50 = 1.7.
The regulation states the same idea from the other side. A footnote to the reference daily intake table in 21 CFR 101.9 defines 1 DFE = 1 mcg naturally occurring folate = 0.6 mcg folic acid. The same section says the nutrient name "folate" covers natural folate, synthetic folate such as the calcium salt of L-5-MTHF, folic acid, or a mix of them.
The parentheses carry folic acid only. FDA's worked example for a folic acid supplement prints "Folate 680 mcg DFE (400 mcg folic acid) 170%". A product with only calcium L-5-MTHF prints "Folate 340 mcg DFE 85%" with no parentheses, and a mix of food folate, folic acid and L-5-MTHF prints "Folate 475 mcg DFE (100 mcg folic acid) 119%". A DFE total with no parentheses does not tell you how many micrograms of methylfolate are inside.
On a supplement, %DV rounds to the nearest whole percent, per a footnote in the same guidance. Conventional foods follow different rounding, which is why two of FDA's food examples print 90% and 25% where the supplement rule gives 85% and 23%. For the rest of the panel, our supplement label reading guide walks through each line.
Common label numbers, converted
The table converts the DFE numbers that show up most often on folate labels and in searches. Label examples are as entered in DSLD and were checked October 29, 2026; a DSLD entry records one label version, not necessarily the bottle on the shelf today.
| Label says (mcg DFE) | Folic acid, FDA formula (÷ 1.7) | Folic acid, 0.6 rule (× 0.6) | % DV, adults and children 4+ | % DV, pregnancy and lactation labels | Where this number shows up |
|---|---|---|---|---|---|
| 400 | 235 | 240 | 100% | 67% | Adult Daily Value; Carlson Methyl Folate 400 mcg (methylfolate, no mass printed) |
| 600 | 353 | 360 | 150% | 100% | Pregnancy and lactation Daily Value; NIH ODS RDA in pregnancy |
| 665 | 391 | 399 | 166% | 111% | Nature Made Folic Acid 400 mcg, which prints 167% |
| 667 | 392 | 400 | 167% | 111% | 400 mcg folic acid by the 0.6 rule |
| 680 | 400 | 408 | 170% | 113% | FDA example 4; The Vitamin Shoppe Folic Acid 400 mcg |
| 800 | 471 | 480 | 200% | 133% | Nature’s Way Folate 800 mcg DFE (480 mcg folic acid) |
| 1,000 | 588 | 600 | 250% | 167% | Nutricost Methyl Folate (panel says 1000 mcg DFE, no separate mass) |
| 1,333 | 784 | 800 | 333% | 222% | Solgar, Nature’s Bounty and Puritan’s Pride (800 mcg folic acid) |
| 1,360 | 800 | 816 | 340% | 227% | 800 mcg folic acid by the 1.7 formula (NIH ODS range); Lake Avenue Methyl Folate (methylfolate) |
| 1,667 | 981 | 1,000 | 417% | 278% | 1,000 mcg folic acid by the 0.6 rule (NIH ODS); BulkSupplements Folic Acid 1000 mcg; Pure Encapsulations Folate 1,000 (methylfolate) |
| 1,700 | 1,000 | 1,020 | 425% | 283% | 1,000 mcg folic acid by the 1.7 formula; Brainchild and Seeking Health methylfolate, 1,000 mcg |
For a methylfolate label, the two folic acid columns are right only if the brand used that factor. The 665 row is a real label oddity: Nature Made prints 665 mcg DFE and 167% for 400 mcg of folic acid, which matches neither 667 nor 680, and we could not find the rounding rule behind it.
Why one bottle says 1,333 and another says 1,360
Take 800 mcg of folic acid. FDA's formula gives 800 × 1.7 = 1,360 mcg DFE, and the regulation's footnote gives 800 ÷ 0.6 = 1,333 mcg DFE. Both numbers come out of FDA's own texts. In the 2016 final rule on the new labels, FDA wrote the two as one rule, concluding that "using the conversion factor of 0.6 mcg (multiply by 1.7) for folic acid is appropriate." 1.7 is also 1 ÷ 0.6 rounded to one decimal place.
Labels split along that line. As entered in DSLD, Solgar's Folate 1,333 mcg DFE, Nature's Bounty Folic Acid 800 mcg and Puritan's Pride Folate 1333 mcg DFE all print 1,333 mcg DFE (800 mcg folic acid) and 333%. The Vitamin Shoppe's Folic Acid 400 mcg prints 680 mcg DFE and 170%, the 1.7 figure.
Other labels use the 0.6 rule at other amounts. Nature's Way Folate 800 mcg DFE reaches 800 from 480 mcg of folic acid, and a BulkSupplements folic acid 1 mg product prints 1,667 mcg DFE and 417%. Nature Made Prenatal Folic Acid prints a third figure for 800 mcg, 1,330 mcg DFE, with 222%: a %DV calculated against the 600 mcg DFE pregnancy and lactation Daily Value instead of the adult 400.
NIH ODS uses both conventions on one page: "680 to 1,360 mcg DFE (400 to 800 mcg folic acid)" for common adult supplement amounts, and "1,000 mcg is equivalent to 1,667 mcg DFE" in its section on upper limits. We found no FDA sentence that names one of the two numbers as the required one, so we do not call either label wrong. Older DSLD entries, such as Spring Valley folic acid labels entered in 2016 and 2018, list folic acid in mcg with no DFE line at all.
Methylfolate: why there is no single answer
Methylfolate labels are the hardest to convert, because no official DFE factor exists for methylfolate. In the 2016 final rule, FDA said it would consider synthetic folates such as L-5-MTHF, and the need for a conversion factor for each, in a separate rulemaking. Until then it does not intend to object to a manufacturer's own established factor if the declaration is truthful and not misleading, and it would "not expect a conversion factor to exceed 1.7 (comparable to folic acid)" (81 FR 33908 to 33909). The 2019 guidance repeats this and notes that 1.7 in its methylfolate examples "was used as an example."
We checked whether that separate rulemaking ever happened. As of October 29, 2026, we found no FDA rule that sets a factor. The eCFR text of 21 CFR 101.9, current to October 27, 2026, names the calcium salt of L-5-MTHF only in the rule on what to call the nutrient. A Federal Register full text search from May 28, 2016 to October 29, 2026 returned no documents for "L-5-MTHF"; "methyltetrahydrofolate" returned one, a 2025 drug approval notice, and "dietary folate equivalents" returned three, none of which sets a methylfolate factor.
NIH ODS says the same: "Factors for converting mcg DFE to mcg for supplemental folate in the form of 5-MTHF have not been formally established."
Labels show the spread. As entered in DSLD, Brainchild Nutritionals and Seeking Health print 1,700 mcg DFE for 1,000 mcg of methylfolate, a factor of 1.7. Pure Encapsulations Folate 1,000 prints 1,667 mcg DFE for 1,000 mcg of L-5-MTHF, and Thorne 5-MTHF 5 mg prints 8.3 mg DFE for 5 mg, both close to 1 ÷ 0.6. Carlson Methyl Folate and Nutricost Methyl Folate print only a DFE number, so their methylfolate mass cannot be backed out; Nutricost's product name says "Methyl Folate 1,000 mcg" while its Supplement Facts row says 1000 mcg DFE.
So the calculator does what the labels allow. With a printed methylfolate amount, it shows the factor the brand used. Without one, it shows two lines, one for each convention. We could not find an official factor for methylfolate, so we will not invent one. If you are weighing the forms themselves, our methylfolate vs folic acid guide covers that question.
With food or on an empty stomach
The 0.6 and 1.7 figures assume folic acid taken with food. The Food and Nutrition Board definitions, as quoted by NIH ODS, are: 1 mcg DFE = 1 mcg food folate; 1 mcg DFE = 0.6 mcg folic acid from fortified foods or supplements consumed with food; and 1 mcg DFE = 0.5 mcg folic acid from supplements taken on an empty stomach. ODS estimates that at least 85% of folic acid is bioavailable with food and nearly 100% without it.
By that last definition, 400 mcg of folic acid on an empty stomach counts as 800 mcg DFE. Comments on the 2016 rule asked FDA to use a factor of 2.0 for supplements taken on an empty stomach. FDA replied that it does not know how many people take folic acid with or without a meal, and kept 0.6 (multiply by 1.7) for consistency across labels. FDA's label rule does not use the empty stomach number, so the calculator shows it as a grey note in the folic acid tab and never as a result.
Daily Value and upper limit, as reference lines
The Daily Value for folate is 400 mcg DFE for adults and children 4 and older, and 600 mcg DFE for pregnant and lactating women, from the reference daily intake table in 21 CFR 101.9. NIH ODS lists the RDA as 400 mcg DFE for adults, 600 mcg DFE in pregnancy and 500 mcg DFE during lactation, which is the plain meaning of "600 mcg DFE" on a prenatal label. Whether a given amount fits your pregnancy is your clinician's call, not this page's.
The upper limit is counted differently. ODS explains that the Food and Nutrition Board set a UL for the synthetic forms of folate available in dietary supplements and fortified foods, and none for folate from food. For adults 19 and older, including during pregnancy and lactation, that UL is 1,000 mcg a day, and it is in mcg, not mcg DFE. ODS also notes that the ULs do not apply to people taking high doses of supplemental folate under medical supervision.
That unit switch is why the calculator shows the UL only as a reference line and never compares it with a DFE number. For methylfolate the label often prints no mass and no factor has been set, so the same line appears there without a comparison. For the vitamin itself, see our complete guide to folate.
Check the numbers
These are cases we ran against the calculator code before publishing, and you can repeat them in the tool above. Each expected value comes from FDA's 2019 guidance or from a label as entered in DSLD on October 29, 2026; the full set of 21 cases runs as an automated check on the code.
| Input | Calculator output | Where the expected number comes from |
|---|---|---|
| I know mcg folic acid: 400 | 667 to 680 mcg DFE; 170% at 680 | FDA example 4 (680 mcg DFE, 170%); The Vitamin Shoppe label (680) |
| Build the label line: food folate 5, folic acid 50 | Folate 90 mcg DFE (50 mcg folic acid) 23% | FDA example 3, enriched flour; the food label rounds to 25% |
| Build the label line: L-5-MTHF 200 at factor 1.7 | Folate 340 mcg DFE 85%, no parentheses | FDA example 5 |
| Build the label line: food folate 50, folic acid 100, L-5-MTHF 150 at 1.7 | Folate 475 mcg DFE (100 mcg folic acid) 119% | FDA example 6 |
| My label shows mcg DFE: 1,333, folic acid | About 784 to 800 mcg folic acid; 333% | Solgar, Nature’s Bounty and Puritan’s Pride labels: 800 mcg folic acid, 333% |
| My label shows mcg DFE: 1,330, folic acid, 800 in parentheses | 800 mcg folic acid, label factor 1.66; 222% of 600 mcg DFE | Nature Made Prenatal Folic Acid label |
| My label shows mcg DFE: 1,700, methylfolate, 1,000 printed | No single answer; label factor 1.70 | Brainchild Nutritionals and Seeking Health labels |
| Build the label line: other synthetic folate at factor 2.0 | Error: FDA would not expect a factor above 1.7; no total | FDA guidance, page 5; 81 FR 33909 |
FAQ
What does 600 mcg DFE mean?
It means the folate in one serving adds up to 600 micrograms of dietary folate equivalents. If all of it is folic acid, that is about 353 to 360 mcg of folic acid. 600 mcg DFE is also the Daily Value used on pregnancy and lactation labels and the RDA in pregnancy listed by NIH ODS.
Is 600 mcg DFE the same as 360 mcg of folic acid?
Under the 0.6 rule in 21 CFR 101.9, yes: 600 × 0.6 = 360 mcg. Under FDA's 1.7 formula, 600 mcg DFE is about 353 mcg of folic acid. Both numbers come from FDA texts. If the label prints folic acid in parentheses, that printed number is the amount.
What does 1,333 mcg DFE mean?
It is the DFE for 800 mcg of folic acid under the 0.6 rule, because 800 ÷ 0.6 = 1,333. Under the 1.7 formula the same 800 mcg is 1,360 mcg DFE. Read in reverse, 1,333 mcg DFE is about 784 to 800 mcg of folic acid and 333% of the adult Daily Value.
How do I convert methylfolate DFE to mcg?
You can convert it exactly only when the label prints the methylfolate amount. No official DFE factor has been set for methylfolate, and FDA has said it would not expect a brand's own factor to exceed 1.7. Without a printed amount, the calculator shows two possibilities: mcg DFE ÷ 1.7 and mcg DFE × 0.6.
How do I convert mcg DFE to mg?
Divide by 1,000. A label line of 1,700 mcg DFE is 1.7 mg DFE, and one Thorne methylfolate label in DSLD prints its folate as 1.7 mg DFE. The unit stays DFE: moving to milligrams does not turn the number into milligrams of folic acid.
Why does folic acid count 1.7 times more than food folate?
FDA puts folic acid at 85 percent bioavailable and folate from food at about 50 percent, and 85 ÷ 50 = 1.7. The Food and Nutrition Board definitions behind DFE also count folic acid taken on an empty stomach at double, but FDA kept one factor for all labels.
Sources and corrections
Conversion factors, label formats and the Daily Value come from FDA documents and the regulation text. The upper limit and the Food and Nutrition Board definitions come from NIH ODS. Label examples come from DSLD.
- FDA, Converting Units of Measure for Folate, Niacin, and Vitamins A, D, and E on the Nutrition and Supplement Facts Labels: Guidance for Industry, August 2019, page 5 and examples 1 to 6.
- 21 CFR 101.9 in the eCFR, text current to October 27, 2026: the folate row of the reference daily intake table and footnote 7.
- FDA final rule, Food Labeling: Revision of the Nutrition and Supplement Facts Labels, 81 FR 33742, May 27, 2016, pages 33908 to 33910.
- Federal Register full text search for "L-5-MTHF", "methyltetrahydrofolate", "synthetic folate" and "dietary folate equivalents", publication dates May 28, 2016 to October 29, 2026, run October 29, 2026.
- NIH Office of Dietary Supplements, Folate Fact Sheet for Health Professionals, updated November 30, 2022, read October 29, 2026.
- NIH DSLD label entries, checked October 29, 2026: 241080, 239045, 286282, 221412, 270953, 280357, 213414, 312971, 184894, 284181, 284182, 328551, 322654, 306355, 209228, 299360, 82861 and 66355.
Published November 3, 2026. Label entries in DSLD, the eCFR text and the Federal Register search were checked October 29, 2026; no registry listing is cited on this page. Corrections will be logged here with a date. Our method is described on how we review supplements.
