Vitamin D Dosage Calculator
This range is for general maintenance only. Correcting a confirmed deficiency often uses a short-term higher-dose protocol supervised by a clinician — this calculator does not generate that dose for self-administration. Talk to your healthcare provider.
RDA and UL from the IOM (National Academies) Dietary Reference Intakes. The 2024 Endocrine Society guideline notes most healthy adults under 75 don't need more than this RDA and don't need routine testing. The at-risk maintenance range (1,500-2,000 IU/day) reflects Endocrine Society guidance for people at confirmed risk of deficiency. This is general health information, not medical advice.
Free vitamin D dosage calculator using IOM (National Academies) RDA and UL figures, plus Endocrine Society guidance for confirmed deficiency — see your recommended daily intake by age, and how it changes if a blood test has confirmed you're deficient.
How it works
- Pick your age band: 1-70, or 71+
- Tell it whether a blood test has confirmed you're vitamin D deficient
- See your IOM RDA and upper limit (UL), plus an Endocrine Society at-risk maintenance range if deficiency is confirmed
Frequently asked questions
How much vitamin D should I take per day?
The IOM (National Academies) Recommended Dietary Allowance is 600 IU/day for ages 1-70 and 800 IU/day for ages 71+. The 2024 Endocrine Society guideline says most healthy adults under 75 don't need more than this RDA and don't need routine blood testing to check their level.
What if my blood test shows I'm actually deficient?
That's a different situation from general prevention. Clinical guidance for people at confirmed risk points to a higher maintenance range of roughly 1,500-2,000 IU/day. Some clinicians use short-term higher-dose protocols (like 50,000 IU/week) to correct a deficiency faster, but those require medical supervision — this calculator doesn't generate that number for you to self-administer.
What's the safe upper limit?
The IOM sets the Tolerable Upper Intake Level (UL) for adults at 4,000 IU/day from supplements. The at-risk maintenance range above stays comfortably under that limit.
How common is vitamin D deficiency in the US?
Based on NHANES data spanning 2001-2018 (over 71,000 participants), about 24.6% of US adults are deficient (22.0% moderate + 2.6% severe) and another 40.9% are insufficient — together over 60% fall short of sufficient levels.
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2026-09-23Update history
- 2026-09-23 Launched: vitamin D dosage calculator using IOM RDA/UL and Endocrine Society at-risk guidance, distinguishing general prevention (2024 guideline) from confirmed-deficiency maintenance dosing, with a medical-supervision note for high-dose correction protocols.