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About this tool
Convert 25-OH vitamin D between ng/mL and nmol/L and see which deficiency, insufficiency or sufficiency band the level falls in.
The Vitamin D Unit Converter changes a serum 25-hydroxyvitamin D result between the conventional unit ng/mL and the SI unit nmol/L using the exact molar-mass factor of 2.496, derived from the 400.64 g/mol molar mass of calcifediol. It then places the level against the Endocrine Society bands (deficiency below 20 ng/mL, insufficiency 20-29 ng/mL, sufficiency 30-100 ng/mL) and the Institute of Medicine cut-points. It is for anyone comparing a lab report against a guideline, a study or an earlier test that used the other unit system.
Open Vitamin D Unit Converter on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Uses 2.496 from the calcifediol molar mass, and also shows the rounded 2.5 result labs print.
Marks the level against both Endocrine Society and Institute of Medicine cut-points, which differ.
Invalid or implausible entries show a plain-language reason instead of a misleading figure.
Multiply the ng/mL figure by 2.496 to get nmol/L, and divide by 2.496 to go the other way. The factor comes from the 400.64 g/mol molar mass of 25-hydroxyvitamin D3, so 30 ng/mL is 74.9 nmol/L and 20 ng/mL is 49.9 nmol/L. Many reports round the factor to 2.5.
The Endocrine Society calls 30-100 ng/mL (75-250 nmol/L) sufficient, 20-29 ng/mL insufficient and below 20 ng/mL deficient. The Institute of Medicine sets a lower bar, treating 20 ng/mL (50 nmol/L) as adequate for bone health in most healthy people, which is why two reports can label the same number differently.
Almost exactly: 20 ng/mL converts to 49.92 nmol/L, which guidelines round to 50 nmol/L. That rounding is why the deficiency threshold is quoted as 20 ng/mL in one unit system and 50 nmol/L in the other.
Levels above 100 ng/mL (250 nmol/L) are above every target range, and vitamin D intoxication with raised blood calcium is generally seen above 150 ng/mL (375 nmol/L). A high result usually follows prolonged high-dose supplementation; stop guessing at doses and ask your doctor to review the result and your calcium level.
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