Vitamin D (25-hydroxy) optimal range and reference range

Compiled by Alina Radu, founder of Sera, from the published sources below · Last reviewed November 9, 2026

Sera's bands for Vitamin D (25-hydroxy):

  • Optimal 50 – 80 ng/mL (50 – 80 μg/L); sufficient 30 – 100 ng/mL (30 – 100 μg/L); out of range below 30 or above 100 ng/mL.

Evidence grade: Functional / longevity target. A narrower target in common use in functional, integrative, preventive and longevity practice. It is not a universally validated diagnostic range.

All units

UnitOptimalSufficientOut of range
ng/mL50 – 8030 – 100below 30 or above 100
μg/L50 – 8030 – 100below 30 or above 100
nmol/L125 – 20075 – 250below 75 or above 250

What the evidence says

The optimal band of 50 to 80 ng/mL (125 to 200 nmol/L) is a functional target, widely used in functional and integrative practice, and it sits above what mainstream bodies recommend. The US National Academies consider 20 ng/mL (50 nmol/L) sufficient for most people and note possible adverse effects above 50, and Mayo Clinic Laboratories lists 51 to 80 ng/mL as carrying an increased risk of hypercalciuria. The 2024 Endocrine Society guideline found no clear evidence defining an optimal level. Sera's acceptable band starts at 30 ng/mL, where the older Endocrine Society guideline placed sufficiency, so a result of 20 to 29 is flagged here though the National Academies would call it adequate. The upper edge of 100 ng/mL is the top of the Labcorp reference range.

Sources

  • Vitamin D - Health Professional Fact Sheet — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates the National Academies position: 50 nmol/L (20 ng/mL) or more is sufficient for most people, deficiency risk rises below 30 nmol/L (12 ng/mL), and levels above 125 nmol/L (50 ng/mL) can be associated with adverse effects. Supports a sufficient lower edge of 20 and an optimal upper edge of 50 ng/mL. Updated June 27, 2025.
  • 25HDN - 25-Hydroxyvitamin D2 and D3, Serum: Clinical & Interpretive — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceClinical decision values based on the 2011 Institute of Medicine report: below 10 ng/mL severe deficiency, 10 to 19 mild to moderate deficiency, 20 to 50 optimum, 51 to 80 increased risk of hypercalciuria, above 80 toxicity possible. Sera's current optimal band of 50 to 80 is Mayo's caution band.
  • Vitamin D, 25-Hydroxy — Labcorp, 2026 · Laboratory / reference-interval sourcePrints reference ranges of 20.0 to 100.0 ng/mL and 30 to 100 ng/mL, and states deficiency is below 20 ng/mL (Institute of Medicine) with 21 to 29 called insufficiency by the older Endocrine Society guideline. Matches Sera's sufficient band of 30 to 100 and supports the upper edge of 100.

What Vitamin D3 (25-Hydroxy Vitamin D) measures

The main form of vitamin D that circulates in your blood.

Vitamin D deficiency is very common and affects your immune system, bones, mood, and energy.

Related vitamins & minerals markers

See Vitamin D (25-hydroxy) in the full list of biomarker ranges

About the author

Alina Radu is the founder of Sera and a software engineer. The idea started with her own Hashimoto's tests, scattered across years without the big picture. She is not a clinician: these ranges are compiled from the published sources linked on each page, with every source named. Alina Radu on LinkedIn

This page is a reference for practitioners, not medical advice. Sera's bands are practitioner targets for structured review, not diagnostic thresholds, and Sera does not diagnose or recommend treatment. Read a result alongside the interval printed by the issuing laboratory and the client's history and symptoms. Range set: Sera Production, version 1.0, last reviewed November 9, 2026.