Vitamin D Intake Levels: IU vs mcg and What Official Bodies Say for Different Ages and Countries
How vitamin D amounts are measured in IU and mcg, and what the US, Canada, UK and EU official bodies publish for each age group, with upper limits and sources.
Content last updated . This page has not been medically reviewed.
Evidence labels used on this page: established nutritional role, evidence in adequately nourished people, insufficient evidence.
IU and mcg: reading the units
Vitamin D amounts appear in micrograms (mcg or µg) and International Units (IU). The NHS says 1 microgram equals 40 IU, so 10 micrograms is 400 IU. [1] Blood levels use a different unit again: MedlinePlus says 25-hydroxyvitamin D (25(OH)D) is reported in ng/mL or nmol/L, where 0.4 ng/mL equals 1 nmol/L. [2] See Vitamin units explained for other vitamins.What each body publishes
Two different kinds of number appear in the tables below. A Recommended Dietary Allowance (RDA) is, in Health Canada's wording, the daily amount "required to meet the needs of about 97.5% of the population." [3] An Adequate Intake (AI) is used when the evidence is not enough to set an RDA. [2]| Body and year | Group | Published level |
|---|---|---|
| US Dietary Reference Intakes via MedlinePlus (page reviewed 2025) | Infants 0 to 12 months (AI) | 400 IU (10 mcg) a day [2] |
| Same | Adults over 70 years (RDA) | 800 IU (20 mcg) a day [2] |
| Same | Pregnancy and breastfeeding (RDA) | 600 IU (15 mcg) a day [2] |
| Health Canada notice, 2021 (same DRI table) | Children and adults 9 to 70 years (RDA) | 600 IU (15 µg) a day [3] |
| Same | Children 1 to 3 years | 600 IU (15 µg) a day [3] |
| Same | Infants 7 to 12 months (AI) | 400 IU (10 µg) a day [3] |
| NHS (UK), page last reviewed 2020 | Children from 1 year and adults, including pregnancy and breastfeeding | 10 micrograms (400 IU) a day [1] |
| Same | Babies up to 1 year | 8.5 to 10 micrograms a day [1] |
| EFSA (EU) Dietary Reference Values, version 4, 2017 | Adults, pregnancy and lactation (AI) | 15 µg a day [4] |
EFSA's table notes that its vitamin D values apply "under conditions of assumed minimal cutaneous vitamin D synthesis," meaning little vitamin D made by skin from sunlight. [4] The NHS says most people in the UK can make what they need from sunlight from about late March or early April to the end of September, but not from October to early March. [1] Sunlight production varies a great deal from person to person. [2] See Vitamin D and sunlight.
Other statements you may see:
- Daily Value on US labels. The FDA lists 20 mcg as the Daily Value for vitamin D. This is a reference amount for label percentages, not a personal requirement. [5]
- A foundation's higher figure. MedlinePlus notes that the Bone Health and Osteoporosis Foundation recommends 800 to 1,000 IU daily for people 50 and older, and says to ask a health care provider which amount is best. [2]
- UK seasonal advice. The NHS says everyone, including pregnant and breastfeeding women, should consider a daily 10 microgram supplement in autumn and winter. [1]
- Endocrine Society guideline (2024). The panel suggests empiric supplementation for children aged 1 to 18, adults over 75, pregnancy and high-risk prediabetes. It suggests against going above the current intake references to lower disease risk in healthy adults under 75. It is not meant to replace the intake references, nor to apply to people with established indications for treatment. [6]
Upper limits (not targets)
An upper limit (UL) is the most that is not expected to cause harm for most people over time. EFSA defines it as the "maximum level of total chronic daily intake of a nutrient." [7] It is not a goal.| Body and year | Group | Upper limit |
|---|---|---|
| Health Canada notice, 2021 (US DRI table) | Children and adults 9 to 70, over 70, pregnancy and lactation | 4,000 IU (100 µg) a day [3] |
| Same | Children 1 to 3 years; infants 7 to 12 months | 2,500 IU (63 µg); 1,500 IU (38 µg) [3] |
| NHS (UK), 2020 | Adults, pregnancy, breastfeeding and ages 11 to 17 | 100 micrograms (4,000 IU) [1] |
| Same | Ages 1 to 10; infants under 12 months | 50 micrograms (2,000 IU); 25 micrograms (1,000 IU) [1] |
| EFSA overview, August 2025 | Adults, pregnancy, lactation and ages 11 to 17 | 100 µg a day [7] |
| Same | Ages 1 to 10; infants 7 to 11 months; 0 to 6 months | 50 µg; 35 µg; 25 µg a day [7] |
The adult limits agree at 100 micrograms (4,000 IU); the figures for babies and young children differ slightly between bodies. What happens above these levels is on Vitamin D toxicity.
Amounts used in studies are not advice
The large VITAL trial gave adults 2,000 IU a day and reported no excess hypercalcemia or other adverse events over a median 5.3 years. [8] That is a study amount in a specific group, not a recommendation, and it does not transfer to everyone.Frequently asked questions
How many IU is 10 micrograms of vitamin D?
The NHS says 1 microgram equals 40 IU, so 10 micrograms is 400 IU. [1]
Why do the US and the UK give different vitamin D numbers?
They come from different expert groups and different age bands. The US and Canada list 600 IU (15 mcg) for most people from age 1 to 70, while the NHS lists 10 micrograms (400 IU). [2][3][1]
What is the difference between an RDA and an upper limit?
An RDA is the amount that meets the needs of about 97.5% of a group. An upper limit is the most that is not expected to cause harm, and it is not a goal. [3][7]
Is the 20 mcg on a US label what I need?
No. It is the label Daily Value, a reference for percentages. [5]
Should I take more than the official levels?
That is a question for a clinician or pharmacist. The Endocrine Society guideline suggests against going above current intake references to lower disease risk in healthy adults under 75, though it does not apply to people with established indications for treatment. [6]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and who should ask first
- Medicines and conditions. The NHS says some medical conditions mean a person may not safely take as much. [1] Kidney or liver disease can affect how the body converts vitamin D, and certain statins, steroids and weight-loss medicines can affect levels. [9] See Medication interactions and tell your provider or pharmacist about every supplement. [9]
- Pregnancy, babies and children. Use the amounts above only as published for those groups, and ask the care team. See Pregnancy and breastfeeding and Vitamin D and K for newborns.
- Testing. Routine vitamin D testing is not recommended for everyone. [9] See Vitamin D deficiency and testing.
- Products. Check the unit (IU or mcg) and the amount per serving; see Quality testing and certifications.
If a child may have swallowed a large amount of any vitamin, call Poison Help at 1-800-222-1222 (US) or 911 for an emergency.
References
- NHS (UK). Vitamin D. Page last reviewed 3 August 2020. Read 2026-10-22.
- MedlinePlus Medical Encyclopedia (US National Library of Medicine). Vitamin D. Review date 21 January 2025. Read 2026-10-22.
- Health Canada. Notice of amendment: Prescription Drug List, Vitamin D (table "The Dietary Reference Intakes for Vitamin D"). Notice dated 22 February 2021. Read 2026-10-23.
- European Food Safety Authority. Summary of Dietary Reference Values, version 4 (September 2017), Table 9 and Table 11 (vitamin D adequate intakes). Read 2026-10-23.
- US Food and Drug Administration. Daily Value on the Nutrition and Supplement Facts Labels. Read 2026-10-23.
- Demay et al. 2024. Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. PMID 38828931. Read 2026-10-23.
- European Food Safety Authority. Overview on Tolerable Upper Intake Levels as derived by the SCF and the EFSA NDA Panel, version 11, August 2025, Table 3 (vitamins) and Table 1 (calcium). Read 2026-10-23.
- Manson et al. 2019. Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease (VITAL). N Engl J Med. PMID 30415629. Read 2026-10-23.
- MedlinePlus (US National Library of Medicine). Vitamin D Test. Read 2026-10-22.