Type the 25(OH)D result from your blood test and pick the unit printed beside it. You get it in both units and the row of the NIH’s own table it falls in, in the NIH’s words — and a reminder that your lab’s printed range, and your doctor, have the last word.
25 ng/mL is
62.5 nmol/L Generally considered adequate for bone and overall health in healthy individuals (NIH ODS)
| nmol/L | ng/mL | Health status |
|---|
This is not medical advice and it does not diagnose anything. It shows where a number sits in a published table; what your result means for you depends on your lab’s method, your history and your doctor.
NIH’s Office of Dietary Supplements puts a vitamin D blood level (25(OH)D) of 20 ng/mL (50 nmol/L) or more as “generally considered adequate for bone and overall health in healthy individuals”, 12 to under 20 ng/mL as inadequate, under 12 ng/mL as associated with deficiency, and above 50 ng/mL (125 nmol/L) as linked to potential adverse effects. To convert, 1 ng/mL = 2.5 nmol/L.
How to use it
Find the “Vitamin D, 25-hydroxy” line on your blood test, type the number and pick the unit printed beside it — ng/mL on most US reports, nmol/L on most others. You get the result in both units and the row of NIH ODS’s Table 1 it falls in, quoted. Switching the unit converts the number you typed. It does not tell you what to take: that is the conversation with your doctor.
NIH ODS’s table, and the same result in both units
The table NIH ODS prints (fact sheet updated June 27, 2025): under 30 nmol/L (under 12 ng/mL) “associated with vitamin D deficiency”; 30 to under 50 nmol/L (12 to under 20 ng/mL) “generally considered inadequate”; 50 nmol/L or more (20 ng/mL or more) “generally considered adequate”; over 125 nmol/L (over 50 ng/mL) “linked to potential adverse effects, particularly at >150 nmol/L (>60 ng/mL)”. It is one table for every age.
| Result | In nmol/L | NIH ODS row |
|---|---|---|
| 10 ng/mL | 25 nmol/L | Deficiency |
| 12 ng/mL | 30 nmol/L | Inadequate |
| 15 ng/mL | 37.5 nmol/L | Inadequate |
| 20 ng/mL | 50 nmol/L | Adequate |
| 25 ng/mL | 62.5 nmol/L | Adequate |
| 30 ng/mL | 75 nmol/L | Adequate |
| 40 ng/mL | 100 nmol/L | Adequate |
| 50 ng/mL | 125 nmol/L | Adequate |
| 60 ng/mL | 150 nmol/L | Potential adverse effects |
| 80 ng/mL | 200 nmol/L | Potential adverse effects |
Worked examples
- 25 ng/mL (the page’s example) is 62.5 nmol/L — in the row ODS calls adequate for bone and overall health.
- 12 ng/mL is exactly 30 nmol/L — the bottom of the “inadequate” row, not the deficiency row, because ODS’s edge is “under 30”.
- 50 ng/mL is 125 nmol/L — still in the adequate row; ODS’s next row starts above 125.
- A UK result of 40 nmol/L is 16 ng/mL — in the inadequate row, and a conversation with your doctor.
Common mistakes
- Mixing the units. 30 ng/mL and 30 nmol/L are very different results. The unit is printed next to the number.
- Reading one result as a verdict. NIH ODS: “a finding can be falsely low or falsely high, depending on the assay used and the laboratory.”
- Using this table instead of your lab’s. Your report prints its own reference range; that is the one your doctor reads it against.
- Treating a low number yourself. Whether and how much to supplement is your doctor’s call — and a test in healthy people is not routinely advised by the Endocrine Society.
Frequently asked questions
What is a normal vitamin D level?
NIH ODS calls 20 ng/mL (50 nmol/L) or more “generally considered adequate for bone and overall health in healthy individuals”, and links levels above 50 ng/mL (125 nmol/L) to potential adverse effects. Your lab’s own printed range is the one your doctor will use.
What are normal vitamin D levels by age?
NIH ODS’s table is the same for every age; it prints no separate ranges for children, adults or older adults. What changes with age is the recommended intake — see the Vitamin D Dose Calculator.
What is an optimal vitamin D level?
No official table we read names an “optimal” level. NIH ODS uses “adequate” for 20 ng/mL (50 nmol/L) and above, and the Endocrine Society (2024), as ODS reports it, “has not identified 25(OH)D concentrations associated with vitamin D sufficiency, insufficiency, and deficiency”.
How do I convert nmol/L to ng/mL?
Multiply nmol/L by 0.4 to get ng/mL, and ng/mL by 2.5 to get nmol/L. NIH ODS: “One nmol/L = 0.4 ng/mL, and 1 ng/mL = 2.5 nmol/L.”
Is a vitamin D level of 25 ng/mL low?
25 ng/mL is 62.5 nmol/L, which NIH ODS’s table puts in the adequate row. Your lab may print a different range; ask your doctor what it means for you.
Why does my lab’s range differ from this table?
Labs set their own reference ranges, and the tests themselves vary: NIH ODS says the assays show “considerable variability” and a result “can be falsely low or falsely high, depending on the assay used and the laboratory”.
What vitamin D level is too high?
NIH ODS links levels above 125 nmol/L (50 ng/mL) to potential adverse effects, “particularly at >150 nmol/L (>60 ng/mL)”, and notes toxicity comes with levels “typically >375 nmol/l [150 ng/mL]”. A high result is a call to your doctor.
Read next
- The Vitamin D Dose Calculator — where a supplement’s IU sits against the RDA and the upper limit.
- Does vitamin D increase dopamine? A look at the science
- Great vitamins for autumn depression
- The best vitamins for women at 30+
- Multivitamins for adults: how to choose
This is not medical advice, and nothing here diagnoses or treats anything. It shows where a number sits in a published table; what it means for you is a conversation with your doctor, who knows your lab’s method and your history. Some links on this site are affiliate links: I buy what I review at full price, and a commission never changes a verdict.