Trying to conceive
Folic Acid Calculator
How much folic acid do you actually need? Five quick questions match you to the published recommendation that applies to you — the CDC standard 400 mcg a day, or the higher provider-prescribed dose some histories call for — plus when to start and how to get it. Nothing you answer leaves your device.
The neural tube closes about 28 days after conception — usually before a test turns positive. That's why the dose question is worth settling before pregnancy, not after.
Folic acid dose quiz
Matched to published CDC, USPSTF, and ACOG folic-acid guidance. This is general information, not medical advice or a prescription — your provider confirms the dose that's right for you, and higher-than-standard doses are always provider-prescribed.
Why it matters
A tiny vitamin with unusually strong proof
Neural-tube defects — spina bifida and anencephaly are the most common — happen when the structure that becomes the brain and spinal cord doesn't close completely. That closure finishes about 28 days after conception, which is the whole reason timing dominates this topic: it's usually done before a pregnancy test turns positive, so starting folic acid after a positive test misses much of the window.
The evidence here is about as strong as nutrition evidence gets. Randomized trials — including the landmark MRC Vitamin Study — showed folic acid prevents a large share of neural-tube defects, cutting recurrence risk by roughly 70% in women who'd had an affected pregnancy. That's why the CDC recommends 400 mcg of folic acid daily for everyone who could become pregnant, not just those actively trying, and why the USPSTF gives folic-acid supplementation its strongest endorsement for people planning or capable of pregnancy.
The quiz above doesn't invent a dose for you — no calculator should. It matches your answers to the published recommendation that covers your situation, flags the histories where a higher provider-prescribed dose is the standard of care, and tells you what to bring to your provider. The dose decision itself, whenever it's anything above 400 mcg, belongs to your OB, midwife, or specialist.
The recommendations
Who gets which published recommendation
These are the published numbers the quiz draws from — CDC and USPSTF for the standard dose, CDC for the post-NTD dose, and ACOG's neural-tube-defect guidance for the conditions where a higher dose is individualized with a clinician.
| Your situation | Published recommendation | How it's done |
|---|---|---|
| Everyone who could become pregnant | 400 mcg folic acid daily (CDC; USPSTF advises 400–800 mcg) | Start at least one month before conception and continue through at least the first trimester. An over-the-counter supplement or prenatal vitamin covers it. |
| A previous pregnancy affected by a neural-tube defect — or you or the baby's other parent has one | 4,000 mcg (4 mg) daily — the published CDC recommendation for this history | Prescription-only, through your provider: from at least one month before trying through the first 3 months of pregnancy. Never self-dose by stacking multivitamins. |
| Taking anticonvulsants or sulfasalazine | 400 mcg is the baseline; a higher dose may be discussed | Ask your neurologist and OB together — and never change or stop seizure medicine on your own. |
| Taking methotrexate | A different kind of problem — this is a medication decision, not a folic-acid dose | Methotrexate causes miscarriage and serious birth defects, and folic acid does not make it safe in pregnancy. Standard preconception guidance is to stop it — on your prescriber's plan, with a washout period — before trying to conceive. Talk to your prescriber and OB first. |
| Diabetes (type 1 or type 2) | 400 mcg is the baseline; a higher dose may be discussed | Raise it at a preconception visit — blood-sugar control before pregnancy matters for the same birth defects. |
| Malabsorption (celiac, Crohn's/IBD) or bariatric surgery | 400 mcg is the baseline; a higher dose may be discussed | Absorption differs after these — your provider may check levels and adjust your dose. |
Three hard rules. The 4 mg dose is prescription-only — never self-dose it, and never try to reach it by taking several multivitamins, which overshoots other vitamins (like vitamin A) that are harmful in pregnancy at high doses. If you take seizure medicine, never change or stop it on your own: the dose conversation belongs with your neurologist and OB together. And methotrexate is different in kind: it's a known cause of miscarriage and serious birth defects that must be stopped — on your prescriber's plan — before trying to conceive, and no folic-acid dose makes it safe in pregnancy.
Supplement vs food
Folic acid, folate, and what food actually delivers
Folate is the natural form of vitamin B9 in food; folic acid is the synthetic form in supplements and fortified grains. They're not interchangeable spoon-for-spoon: natural food folate is absorbed only about half as well, which is why intakes are counted in dietary folate equivalents (DFE) and why the CDC recommendation names 400 mcg of folic acid specifically — a supplement or fully fortified cereal is the dependable way to hit it, with folate-rich food as the bonus on top.
One ceiling to know: unless your provider prescribes more, keep folic acid from supplements and fortified foods under 1,000 mcg a day — the established adult upper limit — because very high self-directed intakes can mask a vitamin B12 deficiency.
| Food | mcg DFE / serving |
|---|---|
| Beef liver, braised, 3 oz | 215 |
| Spinach, boiled, ½ cup | 131 |
| Black-eyed peas, boiled, ½ cup | 105 |
| Fortified breakfast cereal (25% DV serving — some brands 100%) | 100 |
| White rice, enriched, cooked, ½ cup | 90 |
| Asparagus, boiled, 4 spears | 89 |
| Brussels sprouts, boiled, ½ cup | 78 |
| Spaghetti, enriched, cooked, ½ cup | 74 |
| Romaine lettuce, shredded, 1 cup | 64 |
| Avocado, raw, ½ cup | 59 |
| Orange juice, ¾ cup | 35 |
| Egg, hard-boiled, 1 large | 22 |
Values from the NIH Office of Dietary Supplements folate fact sheet. Liver is folate-rich but also very high in vitamin A — worth limiting when pregnant or trying; your provider can advise.
Next steps
Related tools
Preconception checklist
Folic acid is one box — see everything else worth sorting before you start trying.
Prenatal visit schedule
What happens at each prenatal visit, trimester by trimester — including the first-visit labs.
Pregnancy checklist
Newly pregnant? The to-dos that matter each trimester, in one organized list.
All pregnancy tools
The full suite — from timing conception to dating a pregnancy.
Sources
Where this comes from
The doses, timing, and risk situations here are the published recommendations, not our own: the CDC's folic-acid guidance (400 mcg daily for everyone who could become pregnant; 4,000 mcg daily after an NTD-affected pregnancy, under a provider's care), the USPSTF recommendation statement (400–800 mcg for persons planning or capable of pregnancy), and ACOG's neural-tube-defect guidance for the conditions where a higher dose is individualized. Food-folate values come from the NIH Office of Dietary Supplements. We match you to the recommendation that covers your situation — the prescription decisions stay with your provider.
Medically Reviewed & Fact-Checked · Updated
Reviewed by EasySTD Editorial Team
Compiled and checked by EasySTD's editorial team against CDC and public-health sources. This is educational information, not a substitute for advice from a licensed clinician. Our editorial guidelines →
4 Sources
Data & references
- CDC: Folic Acid recommendationshttps://www.cdc.gov/folic-acid/about/index.html
- USPSTF: Folic Acid Supplementation to Prevent Neural Tube Defects (recommendation statement)https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/folic-acid-for-the-prevention-of-neural-tube-defects-preventive-medication
- ACOG: Practice Bulletin No. 187 — Neural Tube Defectshttps://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2017/12/neural-tube-defects
- NIH Office of Dietary Supplements: Folate fact sheethttps://ods.od.nih.gov/factsheets/Folate-HealthProfessional/
EasySTD is an information and comparison directory, not a healthcare provider. This tool is general information based on published CDC, USPSTF, and ACOG guidance: it is not medical advice, a prescription, or a diagnosis, and it does not create a doctor-patient relationship. Doses above the standard 400 mcg are always provider-prescribed — confirm what's right for you at a preconception or prenatal visit.
Good to Know
Folic acid: frequently asked questions
Why it matters before a positive test, how much to take, food vs supplements, what changes after an NTD-affected pregnancy, and how private this is.
Why do I need folic acid before I'm even pregnant?
Because the structure folic acid protects — the neural tube, which becomes the brain and spinal cord — closes about 28 days after conception, usually before a pregnancy test turns positive. If you start folic acid only when you learn you're pregnant, the critical window has often already passed. That's why the CDC recommends 400 micrograms daily for everyone who could become pregnant, ideally beginning at least one month before conception and continuing through the first trimester. It's one of the best-proven prevention steps in all of medicine: randomized trials showed folic acid prevents a large share of neural-tube defects.
How much folic acid should I take?
For most people the answer is simple: 400 micrograms (0.4 mg) of folic acid daily — the CDC recommendation for everyone who could become pregnant, and squarely inside the USPSTF's advised range of 400–800 micrograms for those planning or capable of pregnancy. Most prenatal vitamins and many multivitamins contain at least this much; check the label. The exception is a history of a neural-tube-defect-affected pregnancy, where the published recommendation is 4,000 micrograms (4 mg) daily — a prescription dose your provider manages. Conditions like epilepsy treated with anticonvulsants, diabetes, or malabsorption are worth a dose conversation with your provider too.
Can't I just get enough folate from food?
Food folate is genuinely valuable — leafy greens, beans, asparagus, avocado, and fortified grains all contribute — but it's hard to reliably hit the target from food alone. Natural food folate is absorbed only about half as well as synthetic folic acid, and the amount in a serving varies with cooking and storage. That's why the CDC recommendation is specifically 400 mcg of folic acid — from a supplement, fully fortified cereal, or both — in addition to a folate-rich diet, not instead of one. A daily supplement is the dependable floor; the food is a bonus on top.
I had a pregnancy affected by a neural-tube defect. What's different for me?
The published CDC recommendation for your next pregnancy is 4,000 micrograms (4 mg) of folic acid daily, starting at least one month before you begin trying and continuing through the first three months of pregnancy — in the landmark randomized trial behind it, this cut the risk of recurrence by around 70%. But this is a prescription dose: don't try to reach it yourself, and never by taking multiple multivitamins, which would overshoot other vitamins (like vitamin A) that are harmful in pregnancy at high doses. Ask your OB or midwife for a folic-acid-only prescription at a preconception visit.
Can I take too much folic acid?
For self-directed use, yes, there's a ceiling: 1,000 micrograms (1 mg) a day from supplements and fortified foods is the established upper limit for adults unless a provider prescribes more. Very high intakes can mask a vitamin B12 deficiency — correcting the blood picture while nerve damage continues — which is the main reason not to megadose on your own. The 4 mg dose used after an NTD-affected pregnancy is intentionally above that limit, which is exactly why it's provider-prescribed and time-limited rather than something to self-dose. At the recommended 400 mcg daily, folic acid is considered very safe.
Is what I enter private?
Yes. This tool runs entirely in your browser. Your answers are matched to the published recommendations on your own device and are never sent to a server, saved, or shared — close the tab and they're gone. In a post-Dobbs world we treat reproductive-health data as sensitive by default. The result is general educational information based on CDC, USPSTF, and ACOG guidance; it isn't medical advice or a prescription, and your provider confirms the dose that's right for you.
Have a different question? Browse the full pregnancy FAQ library, every question we answer, in one place.