25(OH)D Test: What Your Vitamin D Level Means (2026)
The 25(OH)D test measures the vitamin D stored in your blood. A result of 20 ng/mL (50 nmol/L) or higher is enough for most people, and below 12 ng/mL (30 nmol/L) is deficient. Each extra 1,000 IU of D3 a day raises the result by about 7 ng/mL, over two to three months.
By Erin Rose Updated October 20, 2026 How we score
What your result means
| ng/mL | nmol/L | What it means |
|---|---|---|
| Below 12 | Below 30 | Deficient. Ask your doctor about treatment. |
| 12 to 19 | 30 to 49 | Low for some people. |
| 20 to 50 | 50 to 125 | Enough for most people. |
| Above 50 | Above 125 | Higher than needed; may cause harm, more so above 60 ng/mL. |
Results can differ a little from lab to lab, so compare tests from the same lab when you can.
What to do with your result
Your result is low: follow your doctor’s plan
Doctors often use 5,000 IU a day for a set time to bring a low level up, then retest. NatureWise D3 5000 IU, one small softgel in olive oil, is on NSF/ANSI 173. It is above the 4,000 IU adult upper limit, so take it only on your doctor’s advice.
NatureWise Vitamin D3 5000 IU in Olive Oil
$0.04 a day · 5,000 IU · NSF/ANSI 173
Your result is in range: keep it there
If your result is in range, 2,000 IU a day is enough to hold it there for most adults, and it is under the 4,000 IU limit. NatureWise D3 2000 IU, on NSF/ANSI 173, is one small softgel.
NatureWise Vitamin D3 2000 IU in Olive Oil
$0.04 a day · 2,000 IU · NSF/ANSI 173
How fast vitamin D3 moves your result
In a careful winter study, each extra 1,000 IU a day raised the result by about 7 ng/mL (Heaney 2003). The level climbs for about two to three months on a steady dose, then levels off, so retest after three months, not three weeks. People who start low rise more, and people with obesity rise less.
Do you need the test?
Most healthy adults do not. The Endocrine Society’s 2024 guideline advises against routine vitamin D testing, including for people with obesity or darker skin (Demay 2024). The US Preventive Services Task Force found too little evidence to say whether testing people without symptoms helps (USPSTF 2021). Your doctor may still test you if you are at higher risk, for example after weight-loss surgery or with a gut condition that blocks fat absorption, like Crohn’s or celiac disease (NIH). Taking 1,000 to 2,000 IU a day does not need a test first.
Questions people ask
How do I convert ng/mL to nmol/L?
Multiply ng/mL by 2.5. So 20 ng/mL is 50 nmol/L, and 30 ng/mL is 75 nmol/L.
Do I need 30 ng/mL?
No. 30 ng/mL was the Endocrine Society’s old target, and it withdrew that target in 2024 because trials did not show it helps (McCartney 2024). The main US standard calls 20 ng/mL enough for most people.
Sources
- NIH Office of Dietary Supplements, “Vitamin D: Fact Sheet for Health Professionals” (Table 1, blood levels). ods.od.nih.gov
- Ross AC, et al. “The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know.” J Clin Endocrinol Metab. 2011. PubMed 21118827
- Heaney RP, et al. “Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol.” Am J Clin Nutr. 2003. PubMed 12499343
- Demay MB, et al. “Vitamin D for the prevention of disease: an Endocrine Society clinical practice guideline.” J Clin Endocrinol Metab. 2024. PubMed 38828931
- McCartney CR, et al. “Vitamin D insufficiency and epistemic humility: an Endocrine Society guideline communication.” J Clin Endocrinol Metab. 2024. PubMed 38828961
- US Preventive Services Task Force. “Screening for vitamin D deficiency in adults: US Preventive Services Task Force recommendation statement.” JAMA. 2021. PubMed 33847711