Type the folate line from a supplement label — folic acid or methylfolate, in mcg, mg or mcg DFE — and who takes it. You see the day in mcg and in mcg DFE, the RDA and the upper limit for that age or pregnancy, and what NIH ODS and the FDA say about each. Your doctor or pharmacist has the last word.
One serving a day is
400 mcg folic acid = 680 mcg DFE 40% of the 1,000 mcg upper limit · 19 years and older
One serving: 400 mcg folic acid = 680 mcg DFE on a label (× 1.7, the factor in NIH ODS’s Daily Value formula), 170% of the 400 mcg DFE Daily Value.
By the FNB’s own definition, the day’s 400 mcg folic acid is 667 mcg DFE taken with food (1 mcg DFE = 0.6 mcg folic acid) or 800 on an empty stomach (0.5).
The RDA for 19 years and older is 400 mcg DFE: the day’s 667 mcg DFE (with food) is 167% of it — above it.
The upper limit for 19 years and older is 1,000 mcg of folate from supplements and fortified foods — in mcg, not mcg DFE: the day’s 400 mcg folic acid is 40% of it — under it.
It counts this label only: the upper limit counts every supplement and fortified food together. NIH ODS: “The fortification program increased mean folic acid intakes in the United States by about 190 mcg/day”.
If you could become pregnant — NIH ODS: “The FNB advises all women and adolescents who are capable of becoming pregnant to ‘consume 400 mcg of folic acid daily from supplements, fortified foods, or both in addition to consuming food folate from a varied diet’”. This label gives 400 mcg folic acid a day, which reaches that 400.
What you take, and how much, is a conversation with your doctor or pharmacist — this places what the label says; it is not a dose.
| Who | RDA (mcg DFE) | Upper limit (mcg, supplements and fortified foods) |
|---|---|---|
| Birth to 6 months | 65 mcg DFE (AI) | Not possible to establish |
| 7–12 months | 80 mcg DFE (AI) | Not possible to establish |
| 1–3 years | 150 mcg DFE | 300 mcg |
| 4–8 years | 200 mcg DFE | 400 mcg |
| 9–13 years | 300 mcg DFE | 600 mcg |
| 14–18 years | 400 mcg DFE | 800 mcg |
| 19 years and older | 400 mcg DFE | 1,000 mcg |
| Pregnant, 14–18 | 600 mcg DFE | 800 mcg |
| Pregnant, 19 and older | 600 mcg DFE | 1,000 mcg |
| Breastfeeding, 14–18 | 500 mcg DFE | 800 mcg |
| Breastfeeding, 19 and older | 500 mcg DFE | 1,000 mcg |
This is not medical advice, and it is not a dose. It converts what a label says and places it against the lines the National Academies set; what you take, and how much, is for you and your doctor or pharmacist.
A label multiplies folic acid by 1.7: 400 mcg folic acid prints as 680 mcg DFE. By NIH ODS’s definitions, 1 mcg DFE = 1 mcg food folate = 0.6 mcg folic acid with food = 0.5 mcg on an empty stomach. The upper limit — 1,000 mcg for adults — counts folic acid in mcg, not DFE, and methylfolate has no set factor.
How to use it
Pick what the label lists — folic acid or methylfolate — and who takes it, then type the amount in one serving with its unit: mcg, mg, or the mcg DFE a Supplement Facts panel prints first. Add how many servings a day, and for folic acid whether it goes down with food. You see the day in mcg and in mcg DFE, the RDA and the upper limit for that age or pregnancy, and the sources’ own sentences beside them. It converts and places what a label says; it is not a dose.
Why a label prints two numbers
NIH ODS: “The FNB developed DFEs to reflect the higher bioavailability of folic acid than that of food folate. At least 85% of folic acid is estimated to be bioavailable when taken with food, whereas only about 50% of folate naturally present in food is bioavailable”. The FDA’s rule (21 CFR 101.9): “The declaration for folate must be in mcg DFE (when expressed as a quantitative amount by weight in a conventional food or a dietary supplement), and percent DV based on folate in mcg DFE.” And: “When folic acid is added or when a claim is made about the nutrient, folic acid must be declared in parentheses, as mcg of folic acid.” So a folic acid label reads “680 mcg DFE (400 mcg folic acid)”. NIH ODS: “The labels must list folate content in mcg DFE per serving and if folic acid is added to the product, they must also list the amount of folic acid in mcg in parentheses.”
The label’s arithmetic is the one NIH ODS gives for the Daily Value: “mcg DFE = mcg naturally occurring folate + (1.7 x mcg folic acid)”. The regulation itself defines “DFE = Dietary Folate Equivalents; 1 DFE = 1 mcg naturally occurring folate = 0.6 mcg folic acid.” — 1 ÷ 0.6 is 1.667, a little under 1.7. That is why 1,360 mcg DFE typed on its own gives 800–816 mcg folic acid here: the folic acid in parentheses is the exact number. “The DV for folate is 400 mcg DFE for adults and children age 4 years and older”; the %DV on a panel is against that 400.
Folic acid to mcg DFE, three ways
| Folic acid (mcg) | On a label (× 1.7) | FNB, with food (÷ 0.6) | FNB, empty stomach (÷ 0.5) |
|---|---|---|---|
| 100 | 170 | 167 | 200 |
| 200 | 340 | 333 | 400 |
| 400 | 680 | 667 | 800 |
| 600 | 1,020 | 1,000 | 1,200 |
| 800 | 1,360 | 1,333 | 1,600 |
| 1,000 | 1,700 | 1,667 | 2,000 |
NIH ODS’s three definitions: “1 mcg DFE = 1 mcg food folate”; “1 mcg DFE = 0.6 mcg folic acid from fortified foods or dietary supplements consumed with foods”; “1 mcg DFE = 0.5 mcg folic acid from dietary supplements taken on an empty stomach”. Food folate needs no conversion.
Methylfolate (5-MTHF)
NIH ODS: “Some dietary supplements also contain folate in the monoglutamyl form, 5-MTHF (also known as L-5-MTHF, 5-methyl-folate, L-methylfolate, and methylfolate).” “Factors for converting mcg DFE to mcg for supplemental folate in the form of 5-MTHF have not been formally established”. “However, conversion factors between mcg and mcg DFE for 5-MTHF have not been formally established. FDA allows manufacturers to use either a conversion factor of 1.7 to be comparable to folic acid or their own established conversion factors not to exceed 1.7”. So a label’s methylfolate in mcg DFE is at most 1.7 times its mcg, and the calculator says “up to” — or “at least”, going the other way. The FDA’s name for it on a panel is folate: “the nutrient name “folate” shall be listed for products containing folate (natural folate, and/or synthetic folate as a component of dietary supplement, such as calcium salt of L-5-MTHF), folic acid, or a mixture of folate and folic acid.”
NIH ODS on how it compares: “The bioavailability of 5-MTHF in supplements is the same as or greater than that of folic acid”. “For some people, supplementation with 5-MTHF might be more beneficial than with folic acid”. On the MTHFR gene variant: “Although the research on the benefits of folate supplementation for people with this genetic polymorphism is inconclusive, some of these people might benefit from supplementation with 5-MTHF”. “However, the Centers for Disease Control and Prevention (CDC) recommends 400 mcg/day of folic acid, not 5-MTHF, for people who could become pregnant, even if they have a 677C>T MTHFR polymorphism”.
The RDA and the upper limit
The RDA is in mcg DFE and counts every source — food folate, fortified foods and supplements. The upper limit does not: NIH ODS: “the FNB established a UL for the synthetic forms of folate available in dietary supplements and fortified foods”. “The FNB did not establish a UL for folate from food because high intakes of folate from food sources have not been reported to cause adverse effects”. “Thus, unlike the RDAs, the ULs are in mcg, not mcg DFE. For folic acid, 1,000 mcg is equivalent to 1,667 mcg DFE because 0.6 mcg folic acid = 1 mcg DFE”. “The ULs do not apply to individuals taking high doses of supplemental folate under medical supervision”.
| Who | RDA (mcg DFE) | Upper limit (mcg, supplements and fortified foods) |
|---|---|---|
| Birth to 6 months | 65 mcg DFE (AI) | Not possible to establish |
| 7–12 months | 80 mcg DFE (AI) | Not possible to establish |
| 1–3 years | 150 mcg DFE | 300 mcg |
| 4–8 years | 200 mcg DFE | 400 mcg |
| 9–13 years | 300 mcg DFE | 600 mcg |
| 14–18 years | 400 mcg DFE | 800 mcg |
| 19 years and older | 400 mcg DFE | 1,000 mcg |
| Pregnant, 14–18 | 600 mcg DFE | 800 mcg |
| Pregnant, 19 and older | 600 mcg DFE | 1,000 mcg |
| Breastfeeding, 14–18 | 500 mcg DFE | 800 mcg |
| Breastfeeding, 19 and older | 500 mcg DFE | 1,000 mcg |
Under 1 year the RDA is an Adequate Intake (AI), and there is no upper limit: “Breast milk, formula, and food should be the only sources of folate for infants.” In pregnancy, “the FNB increased the folate RDA from 400 mcg DFE/day for nonpregnant women to 600 mcg DFE/day during pregnancy”. For anyone who could become pregnant: “The FNB advises all women and adolescents who are capable of becoming pregnant to “consume 400 mcg of folic acid daily from supplements, fortified foods, or both in addition to consuming food folate from a varied diet””. Why the upper limit is there at all: “Large amounts of folate can correct the megaloblastic anemia, but not the neurological damage, that can result from vitamin B12 deficiency.”
Fortified foods count too
The upper limit is the day’s folic acid from every bottle and every fortified food together, and this calculator sees one label. US enriched breads, cereals, flours, corn meals, pastas and rice carry 140 mcg folic acid per 100 g by FDA rule; NIH ODS: “The fortification program increased mean folic acid intakes in the United States by about 190 mcg/day”. On unmetabolized folic acid: “Limited research suggests that single doses of 300 mcg or 400 mcg folic acid (a common amount in folic acid-containing supplements or servings of fortified foods, such as breakfast cereals) result in detectable serum levels of unmetabolized folic acid, whereas doses of 100 mcg or 200 mcg do not”. “These potential negative health consequences are not well understood and warrant further research”.
Medicines
NIH ODS names methotrexate, antiepileptic medications (phenytoin, carbamazepine, valproate) and sulfasalazine as medicines folate interacts with: “Individuals taking these medications on a regular basis should discuss their folate intakes with their health care providers.” This calculator does not check medicines.
Worked examples
- A multivitamin with 400 mcg folic acid, one a day with breakfast, for an adult: 680 mcg DFE on the label, 667 mcg DFE by the FNB’s own factor with food — 167% of the 400 mcg DFE RDA — and 400 mcg against the 1,000 mcg upper limit: 40% of it.
- A prenatal printing “1,360 mcg DFE (800 mcg folic acid)”, pregnant, 19 or older: 800 mcg folic acid is 1,333 mcg DFE with food, 222% of the 600 mcg DFE pregnancy RDA, and 80% of the 1,000 mcg upper limit. Typed as 1,360 mcg DFE alone, it reads 800–816 mcg folic acid (80–82%) until the parentheses settle it.
- A 1 mg folic acid tablet, for an adult: 1 mg is 1,000 mcg — the upper limit itself, printed as 1,700 mcg DFE. The answer carries NIH ODS’s “The ULs do not apply to individuals taking high doses of supplemental folate under medical supervision”.
- 600 mcg L-methylfolate, for an adult: up to 1,020 mcg DFE (the maker’s factor is 1.7 at most), and 60% of the 1,000 mcg upper limit.
- A children’s multivitamin with 200 mcg folic acid (340 mcg DFE), for a child of 4–8: 333 mcg DFE with food against an RDA of 200, and 50% of the 400 mcg upper limit for that age.
Common mistakes
- Holding mcg DFE against the upper limit. The limit is in mcg of folic acid: 1,700 mcg DFE of folic acid is 1,000 mcg — the adult limit itself, not 170% of it.
- Reading mg as mcg. 1 mg is 1,000 mcg. A “folic acid 1 mg” tablet is ten times a “100 mcg” one.
- Counting one bottle. Two products with folic acid, and fortified cereal and bread, all count toward the same upper limit.
- Giving methylfolate one exact DFE number. No factor is established; 1.7 is the most a maker may use, so the honest answer is a ceiling.
- Taking the %DV for the RDA. The %DV on a panel is against 400 mcg DFE; the RDA is 600 mcg DFE in pregnancy, 500 while breastfeeding and lower for children.
Frequently asked questions
Is folate the same as folic acid?
Folic acid is one form of folate. NIH ODS: “Folate, formerly known as folacin and sometimes vitamin B9, is the generic term for naturally occurring food folates and folates in dietary supplements and fortified foods, including folic acid.” “Folic acid is the fully oxidized monoglutamate form of the vitamin that is used in fortified foods and most dietary supplements.”
How do you convert folic acid to DFE?
NIH ODS: “1 mcg DFE = 0.6 mcg folic acid from fortified foods or dietary supplements consumed with foods”; “1 mcg DFE = 0.5 mcg folic acid from dietary supplements taken on an empty stomach”. Labels use 1.7: 400 mcg folic acid is 680 mcg DFE on a panel, 667 by the FNB’s with-food factor.
Why does my label say “680 mcg DFE (400 mcg folic acid)”?
The FDA requires both: folate in mcg DFE, and “folic acid must be declared in parentheses, as mcg of folic acid” when folic acid is added. 400 × 1.7 = 680.
Is methylfolate better than folic acid?
NIH ODS: “The bioavailability of 5-MTHF in supplements is the same as or greater than that of folic acid”, and “For some people, supplementation with 5-MTHF might be more beneficial than with folic acid”. It also quotes the CDC: “the Centers for Disease Control and Prevention (CDC) recommends 400 mcg/day of folic acid, not 5-MTHF, for people who could become pregnant, even if they have a 677C>T MTHFR polymorphism”. Which one you take is a question for your doctor or pharmacist.
How much folic acid is too much?
The upper limit is 1,000 mcg a day from 19 years on, 800 at 14–18, 600 at 9–13, 400 at 4–8 and 300 at 1–3, counting supplements and fortified foods, in mcg. NIH ODS: “The ULs do not apply to individuals taking high doses of supplemental folate under medical supervision”.
Is 1 mg of folic acid too much?
1 mg is 1,000 mcg: the adult upper limit itself, and over the 800 mcg limit at 14–18. Fortified foods come on top. A 1 mg prescription is read with the doctor who wrote it — the upper limits “do not apply to individuals taking high doses of supplemental folate under medical supervision”, NIH ODS writes.
How much folate do you need in pregnancy?
NIH ODS: “the FNB increased the folate RDA from 400 mcg DFE/day for nonpregnant women to 600 mcg DFE/day during pregnancy”, in mcg DFE from food and supplements together. Before pregnancy: “The FNB advises all women and adolescents who are capable of becoming pregnant to “consume 400 mcg of folic acid daily from supplements, fortified foods, or both in addition to consuming food folate from a varied diet””.
Does folate from food count toward the upper limit?
No. NIH ODS: “The FNB did not establish a UL for folate from food because high intakes of folate from food sources have not been reported to cause adverse effects”. It counts toward the RDA: “1 mcg DFE = 1 mcg food folate”.
More on folate: the Folate Level Checker places a serum or red-cell folate result, and the Homocysteine Level Checker the result read with it. Every vitamin’s RDA and upper limit: the Vitamin & Mineral Dose Lookup. B12, the vitamin folate can mask: the Vitamin B12 Level Checker.
Read next
- Vitamin B9 — folate, from food to supplement.
- Folic acid for women and men
- Multivitamins for adults — reading the label.
- The best vitamins for women at 30+
- Mind Lab Pro vs Provasil — methylfolate in one, folic acid in the other.
This is not medical advice, and nothing here diagnoses or treats anything. It converts what a supplement label says and places it against the lines the National Academies set, in NIH ODS’s and the FDA’s words; what you take, and how much, is for you and your doctor or pharmacist. Some links on this site are affiliate links: I buy what I review at full price, and a commission never changes a verdict.