How much vitamin D per day, by age and need

1. 01

   Adults 1-70: the RDA is 600 IU/day

   The RDA for everyone aged 1 to 70, including pregnant and lactating women, is 600 IU/day (15 mcg), the intake the IOM judged sufficient for bone health in 97.5% of the population (IOM 2011; NIH ODS). This is a floor set for the skeleton, not a performance number. It assumes minimal sun exposure, which is the conservative and realistic case for most people at temperate latitudes for much of the year.

2. 02

   Adults 71 and older: 800 IU/day

   From age 71 the RDA rises to 800 IU/day (20 mcg). The increase reflects reduced skin synthesis, lower dietary intake, and a higher fracture risk in older adults. The supplementation evidence for fracture prevention is strongest in this group when vitamin D is combined with calcium and in people who are deficient or in care settings (NIH ODS). For older adults the 800 IU floor is a more meaningful target than it is for the young.

3. 03

   The 4000 IU/day upper limit, and why it exists

   The tolerable upper intake level is 4000 IU/day for adults (IOM 2011). Toxicity comes from supplements, not sun, and presents as hypercalcemia, but it generally requires sustained intake well above the upper limit, often 10,000 IU/day for months (NIH ODS). The upper limit is a safety margin, not a cliff: a single day above it is not dangerous, but routine dosing above 4000 IU/day without a measured deficiency offers no added benefit and carries needless risk.

4. 04

   The practical maintenance dose: 1000-2000 IU/day

   The gap between the 600-800 IU RDA and the 4000 IU upper limit is where most real-world dosing sits. VITAL used 2000 IU/day (Manson et al. 2019), and 1000-2000 IU/day is the common maintenance range clinicians use to comfortably hold a sufficient blood level. This range is low-risk enough to take without a blood test, while still being more likely than the bare RDA to keep serum 25-OH-D in the 30-50 ng/mL target band through winter.

5. 05

   Dose to a blood level, not a fixed pill

   Vitamin D is the rare nutrient where a cheap blood test changes the dose. The marker is serum 25-hydroxyvitamin D: below 20 ng/mL is deficient, 30-50 ng/mL is a common sufficiency target. Correcting a measured deficiency may use a higher loading dose under clinician guidance, then a maintenance dose. Retest 8-12 weeks after a change. Without a test, 1000-2000 IU/day is the sensible default; with one, you can dose precisely instead of guessing.

6. 06

   Pick D3, and price the dose

   For raising and holding blood levels, D3 (cholecalciferol) outperforms D2 (Tripkovic et al. 2012), so choose D3 for maintenance. Take it with a fat-containing meal, since it is fat-soluble. The molecule is a commodity, so price mostly reflects third-party testing and excipients, not potency. Our vitamin D ranking compares verified D3 products by $/1000 IU so you can hit 1000-2000 IU/day for cents. For the full picture of what the nutrient does, see our breakdown of what vitamin D does in the body.

What people ask us next.

Q01

How much vitamin D should I take per day?

The RDA is 600 IU/day for adults aged 1-70 and 800 IU/day from age 71 (IOM 2011; NIH ODS). Common real-world maintenance is 1000-2000 IU/day, the range that more reliably holds a sufficient blood level; VITAL used 2000 IU/day. The tolerable upper limit is 4000 IU/day. Without a blood test, 1000-2000 IU/day of D3 is a reasonable low-risk default for most adults.

Q02

Is 2000 IU of vitamin D per day too much?

No. 2000 IU/day is well under the 4000 IU/day upper limit and is the dose used in the VITAL trial (Manson et al. 2019). It is a common maintenance dose that helps hold serum 25-OH-D in the 30-50 ng/mL target band, especially through winter. It is not a high or risky dose for healthy adults; the risk territory starts well above the 4000 IU/day upper limit.

Q03

How much vitamin D per day to correct a deficiency?

That should be guided by a blood test and a clinician. A measured deficiency (serum 25-OH-D below 20 ng/mL) is often corrected with a higher loading dose for several weeks, then a maintenance dose of 1000-2000 IU/day, with a retest at 8-12 weeks. The correction dose is deliberately higher than maintenance and time-limited, which is why it belongs under clinician oversight rather than open-ended self-dosing.

Q04

Can you take too much vitamin D per day?

Yes, but it takes a lot. Toxicity comes from supplements, not sun, and presents as hypercalcemia. It generally requires sustained intake well above the 4000 IU/day upper limit, often around 10,000 IU/day for months (NIH ODS). Staying at or below 4000 IU/day without a measured deficiency keeps the risk near zero, so routine megadoses are needless.

Q05

Should I take vitamin D with food?

Yes. Vitamin D is fat-soluble, so taking it with a meal that contains some fat improves absorption. Timing of day does not matter much; consistency does. A daily 1000-2000 IU D3 capsule with breakfast or dinner is a simple, effective routine. Choose D3 over D2, which raises and holds blood levels less effectively (Tripkovic et al. 2012).

Q06

Do I need a blood test before deciding the dose?

It is the only way to dose precisely. The marker is serum 25-hydroxyvitamin D; 30-50 ng/mL is a common sufficiency target and below 20 ng/mL is deficient. A maintenance dose of 1000-2000 IU/day is low-risk without testing, but anyone using higher doses or correcting a suspected deficiency should test, then retest in 8-12 weeks. See our what vitamin D does page for how the blood level drives the effect.