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Vitamin D Calculator

Written by Golam Rabbani, Founder & Lead Engineer — Last updated 2026-05-01

Life stage

How to use this vitamin d calculator

  1. Enter the person’s age in years (0–120).
  2. Pick the life stage — standard adult/child, or pregnant/lactating (ages 14–50).
  3. Press “Look up intake” to see the IOM Recommended Dietary Allowance (RDA) and Tolerable Upper Limit (UL), plus the Endocrine Society’s suggested daily-intake range.
  4. Use Copy to save the result line or Reset to clear the form.

About this vitamin d calculator

The vitamin D calculator looks up published daily-intake reference values by age and life stage. It uses two primary sources side by side: the Institute of Medicine (now NASEM) Dietary Reference Intakes for Calcium and Vitamin D (2011), which give the population RDA and the Tolerable Upper Intake Level (UL); and the Endocrine Society Clinical Practice Guideline “Evaluation, Treatment, and Prevention of Vitamin D Deficiency” (Holick MF et al., J Clin Endocrinol Metab 2011), which suggests a higher intake range for individuals at risk of deficiency.

Vitamin D is measured in international units (IU) or micrograms (µg); 1 µg = 40 IU. The tool shows both. RDA values are 400 IU/day for infants, 600 IU/day for ages 1–70, and 800 IU/day for ages 71+. The IOM UL is 4000 IU/day for adults. The Endocrine Society suggests 1500–4000 IU/day for adults at risk of deficiency. This is a published-guidance lookup, not a personalised prescription based on a serum 25(OH)D level.

Worked example: a 35-year-old non-pregnant adult — IOM RDA 600 IU/day, IOM UL 4000 IU/day; Endocrine Society suggested range 1500–4000 IU/day.

This tool is for general information based on published reference intakes and is not a substitute for advice from a qualified clinician, especially if you have known low vitamin D, kidney disease, or are on medications that affect vitamin D metabolism. This calculator is for general educational purposes only and is not medical advice — consult a licensed healthcare professional for personal guidance.

FAQ

What is the difference between the IOM RDA and the Endocrine Society number?
The IOM RDA is the intake estimated to meet the needs of 97.5% of healthy people. The Endocrine Society guideline targets people at risk of deficiency and so recommends a higher daily intake within the same safety ceiling.
What is the Tolerable Upper Intake Level (UL)?
The UL is the highest daily intake the IOM considers unlikely to cause adverse effects in the general population — 4000 IU/day for adults. Routine dosing above the UL should be supervised by a clinician.
Does this tool diagnose vitamin D deficiency?
No. Diagnosis requires a serum 25-hydroxyvitamin D blood test. This tool only surfaces published daily-intake recommendations.
Do pregnant or lactating people need more vitamin D?
The IOM RDA stays at 600 IU/day during pregnancy and lactation, with the same 4000 IU/day UL. The Endocrine Society suggests 1500–4000 IU/day for people at risk of deficiency.
Is my information stored?
No. The lookup runs entirely in your browser.