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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.
Type the 25(OH)D reading into the field and pick ng/mL or nmol/L under 'Unit on the report'.
The Converted level appears with its deficiency, insufficiency or sufficiency band, using the exact 2.496 factor.
The rows below give the Endocrine Society 30 ng/mL target, the IOM 20 ng/mL adequacy cut-point and the rounded 2.5-factor figure.
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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