Iron Dosage Guide (2026): How Much Iron Per Day by Age & Sex
By Erin Rose Updated October 6, 2026 How we score
Adults need 8 mg of iron a day (men, and women over 50) or 18 mg (women 19 to 50), from food and supplements together; 27 mg in pregnancy (NIH). Most people get that from food. To treat low iron found on a blood test, trials and doctors use more: about 60 mg, once a day or every other day. Above 45 mg a day is past the upper limit for healthy adults.
We earn a commission if you buy through our links. It never changes a score or a pick. How we make money
Verified Supplement Data, updated :Adults need 8 mg of iron a day (men and post-menopausal women), 18 mg if menstruating and 27 mg in pregnancy, from food and supplements together. Low iron found on a blood test is treated with about 60 mg of elemental iron, once a day or every other day. A 325 mg ferrous sulfate tablet is 65 mg of iron.
Whether you need any depends on a ferritin blood test. Check the label for the iron per tablet, not the tablet weight. Our iron calculator gives your daily need by age, sex and pregnancy: find your number.
How much iron a day, by age and sex
| Who | Iron a day |
|---|---|
| Men 19 and over | 8 mg |
| Women 19 to 50 | 18 mg |
| Women 51 and over | 8 mg |
| Pregnancy | 27 mg |
| Breastfeeding (19 to 50) | 9 mg |
| Teens 14 to 18 | 11 (boys), 15 (girls) mg |
| Vegetarians and vegans | 1.8 times the amount above |
| Treating low iron (adults) | About 60 mg, once a day or every other day, with a doctor |
| Upper limit, healthy adults | 45 mg |
Plant iron is absorbed less well than iron from meat, which is why NIH sets vegetarians’ needs 1.8 times higher.
Which iron to buy for your dose
Match the bottle to the amount you need. The “Iron” line on the label is the iron itself.
- Check price on Amazon
You want about 18 mg a day
Solgar Gentle Iron 25 mg $0.11 a day
One 25 mg capsule of gentle bisglycinate covers the 18 mg most women with periods need, without the 36 to 65 mg of stronger pills. Not on a public testing list.
- Check price on Amazon
You want a gentle capsule on a testing list
Thorne Iron Bisglycinate 25 mg $0.27 a day
25 mg of bisglycinate, a form that caused fewer stomach complaints in trials of pregnant women. On NSF Certified for Sport + NSF/ANSI 173.
- Check price on Amazon
Your clinician set about 36 mg a day
NOW Iron 36 mg $0.18 a day
The same gentle form with 36 mg in one capsule. Not on a public testing list.
- Check price on Amazon
You want a chewable top-up
OLLY Delightful Iron 18 mg chewable $0.47 a day
18 mg in 2 chewable tablets, the daily need for women 19 to 50. A top-up, not a treatment dose. On NSF/ANSI 173.
- Check price on Amazon
You were told “slow-release iron, 45 mg”
Piping Rock Slow Release Iron 45 mg $0.06 a day
Ferrous sulfate in a slow-release tablet: 45 mg of iron each. On NSF/ANSI 173.
- Check price on Amazon
You were told “325 mg ferrous sulfate”
Nature Made Iron 65 mg $0.06 a day
This is that tablet: 65 mg of iron each. The cheapest per mg of iron here, and the harder form on the stomach. On Informed Choice + USP Verified.
How much iron do you need?
Your daily need depends on age, sex and life stage. This shows your RDA and whether you are in a higher-need group worth a ferritin test. It does not diagnose low iron.
Tablet weight is not the iron
A “325 mg ferrous sulfate” tablet holds 65 mg of iron. The rest of the weight is the compound the iron is bound to. Different forms carry different shares of iron (NIH):
| Form on the label | Iron by weight |
|---|---|
| Ferrous fumarate | 33% |
| Ferrous sulfate | 20% |
| Ferrous gluconate | 12% |
You do not need to do the math: the Supplement Facts panel lists the iron itself on the “Iron” line.
Treating low iron: how much and how often
When a blood test shows low iron, the standard treatment is one tablet a day of ferrous sulfate, which gives 65 mg. Doctors’ guidelines say no form of iron works better than another, and to take it once a day at most (AGA 2024). Older advice was two or three tablets a day. The UK guideline now says one dose of 50 to 100 mg a day, taken on an empty stomach, may be the best balance for most people (BSG 2021). The reason is below.
Every other day may be gentler. Iron raises a hormone, hepcidin, that lowers how much of the next day’s dose is absorbed. In iron-depleted women, a 60 mg dose every other day was absorbed better than the same dose every day (Stoffel 2017). In a 6-month trial, every-other-day iron gave the same gain in iron stores, with fewer stomach side effects and less iron deficiency at the end (von Siebenthal 2023). AGA’s 2024 advice says every-other-day dosing may be better tolerated.
In 198 women with fatigue, ferritin under 50 and no anemia, 80 mg of iron a day for 12 weeks cut fatigue more than a placebo did (Vaucher 2012). How long: UK guidelines advise checking for a rise in hemoglobin within the first 4 weeks, then continuing iron for about 3 months after it is back to normal, to refill the stores (BSG 2021).
The upper limit, and the danger to children
The upper limit for healthy adults is 45 mg of iron a day (NIH). It was set to avoid stomach upset in people who are not low, so a treatment dose above it, such as 65 mg, is taken when a blood test shows low iron and with a doctor checking. Your body loses very little iron, so extra can build up; do not take iron for years without a test.
Iron pills are dangerous to young children. Accidental iron overdose is a leading cause of fatal poisoning in children under 6, as the warning on iron tablets and capsules says. Keep the bottle closed and out of reach.
How to take it
- Keep it apart from calcium. Calcium might interfere with iron absorption, and experts advise taking the two at different times (NIH). That includes calcium supplements and calcium-based antacids.
- Watch your medicines. Iron can make levothyroxine (thyroid) and levodopa (Parkinson’s) work less well, and acid-reducing drugs called PPIs can lower iron absorption (NIH). Ask your pharmacist how far apart to take them.
- Vitamin C is optional. A 2024 guideline for doctors says to add it (AGA 2024); a 2023 review found it did not clearly help, with very low-quality evidence (Loganathan 2023).
- If it upsets your stomach, try every other day, take it with a small meal, or switch to a gentler form. When to take iron.
What the bottles hold
Iron tablets and capsules come in a few common strengths. Of the 25 we score:
| Iron a serving | Products | Brands |
|---|---|---|
| 15 to 22 mg | 5 | OLLY, Garden of Life, NOW, Bluebonnet, Pure Encapsulations |
| 25 to 29 mg | 10 | Nutricost, Klean Athlete, Thorne, Momentous, Nature's Bounty, Feosol, Seeking Health, Solgar, MegaFood, Bluebonnet |
| 36 mg | 3 | Thorne, Sports Research, NOW |
| 45 mg (slow release) | 2 | Piping Rock, Slow Fe |
| 65 mg | 5 | Nature Made, Piping Rock, Nature's Bounty, Feosol, Vitron-C |
Gummies give 8 to 20 mg a serving, with added sugar. Liquids range from 10 mg to 125 mg a serving; NovaFerrum’s 125 mg teaspoon is almost three times the upper limit, a treatment dose to use only with a doctor.
Questions
How much iron should I take a day?
Usually none on top of food, unless a blood test shows low iron. Then the usual dose is one 65 mg tablet, once a day or every other day. The calculator above gives your daily need by age and sex.
Is 65 mg of iron too much?
For someone who is not low, yes: it is above the 45 mg daily upper limit for healthy adults (NIH). For someone a blood test shows to be low, 65 mg (one 325 mg ferrous sulfate tablet) is a standard treatment dose, taken while a doctor checks your levels.
Is 25 mg of iron enough?
It covers the 18 mg daily need of women 19 to 50 with room to spare. For treating low iron it is on the low side: the absorption trials used 60 mg. In pregnant women, 25 mg of bisglycinate kept iron up as well as 50 mg of ferrous sulfate (Milman 2014), but that was prevention, not treatment.
Should I take iron every day or every other day?
Either works; every other day may be gentler. In iron-depleted women, a 60 mg dose every other day was absorbed better than the same dose daily (Stoffel 2017). A later trial found the same gain in iron stores with fewer stomach side effects (von Siebenthal 2023). Doctors’ guidelines say once a day at most (AGA 2024).
Are iron gummies and liquids a good way to take iron?
They suit people who cannot swallow pills, but they hold less iron for the money. The gummies we score give 8 to 20 mg a serving with added sugar; liquids vary from 10 to 125 mg a serving, so read the label. 60 mg of iron costs $1.33 or more as a gummy, against $0.054 as a standard tablet.
Sources
- NIH Office of Dietary Supplements. Iron fact sheet for health professionals (updated September 4, 2025; read October 6, 2026). RDA (Table 1), upper limit (Table 3), forms, interactions.
- DeLoughery TG, et al. AGA Clinical Practice Update on Management of Iron Deficiency Anemia: Expert Review. Clin Gastroenterol Hepatol. 2024. PubMed 38864796
- Stoffel NU, et al. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women. Lancet Haematol. 2017. PubMed 29032957
- von Siebenthal HK, et al. Alternate day versus consecutive day oral iron supplementation in iron-depleted women: a randomized double-blind placebo-controlled study. EClinicalMedicine. 2023. PubMed 38021373
- Vaucher P, et al. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012. PubMed 22777991
- Milman N, et al. Ferrous bisglycinate 25 mg iron is as effective as ferrous sulfate 50 mg iron in the prophylaxis of iron deficiency and anemia during pregnancy. J Perinat Med. 2014. PubMed 24152889
- Snook J, et al. British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults. Gut. 2021. PubMed 34497146
- Loganathan V, et al. Treatment efficacy of vitamin C or ascorbate given as co-intervention with iron for anemia: a systematic review and meta-analysis. Clin Nutr ESPEN. 2023. PubMed 37739692
- Labels: each brand’s page or the NIH Dietary Supplement Label Database, read October 6, 2026. Testing lists: NSF/ANSI 173, NSF Certified for Sport and Informed Choice read October 5, 2026; USP Verified from our copy of September 22, 2026.