Vitamin D norm (25-OH-D)

Enter your vitamin D (25-OH-D) result and choose the units — the calculator shows your status: deficiency, insufficiency, normal or high. ng / mL and nmol / L differ by 2.5×, so choosing the right units matters — the calculator converts automatically.

Check your vitamin D level

Enter your vitamin D level — the result appears instantly.

Vitamin D levels (25-OH-D)

By Endocrine Society classification. 1 ng / mL = 2.5 nmol / L. The optimal range for most people is 30–60 ng / mL.

StatusLevel
Deficiency< 20 ng / mL (< 50 nmol / L)
Insufficiency20–30 ng / mL (50–75 nmol / L)
Normal30–100 ng / mL (75–250 nmol / L)
High> 100 ng / mL (> 250 nmol / L)

What the 25(OH)D test shows

Vitamin D status is assessed by 25-hydroxyvitamin D (25-OH-D) — the main storage form reflecting your supply over recent weeks. Below 20 ng / mL (50 nmol / L) is deficiency, 20–30 ng / mL is insufficiency, and the optimal range for most is 30–60 ng / mL.

Don’t mix up the units: ng / mL and nmol / L differ by 2.5×. A value of 30 nmol / L is deficiency, while 30 ng / mL is already normal. The calculator converts automatically, but choose the units shown on your report.

Why vitamin D deficiency matters

Vitamin D is needed for calcium absorption and bone health, muscle function and immunity. Deficiency is linked to fatigue, muscle and bone pain, rickets in children and reduced bone density in adults. It’s very common, especially in winter and at northern latitudes.

A doctor decides on replenishment

The vitamin D dose for replenishment is chosen individually by level, weight and goal — by a doctor, not a calculator. Taking high doses without monitoring risks overdose (hypercalcemia). At normal levels a maintenance dose is usually enough.

Frequently asked questions

  • A normal 25(OH)D is 30–100 ng / mL (75–250 nmol / L), optimally 30–60 ng / mL for most. Below 20 ng / mL is deficiency, 20–30 is insufficiency. The calculator determines the status and converts units.

  • They’re the same quantity in different units: 1 ng / mL = 2.5 nmol / L. For example, 30 ng / mL = 75 nmol / L. Confusing them is risky: 30 nmol / L is deficiency, while 30 ng / mL is normal. Choose the units on your report.

  • Deficiency is linked to fatigue, muscle and bone pain, reduced bone density and rickets in children. Vitamin D matters for calcium, immunity and muscles. It’s common, especially in winter.

  • The replenishment dose is chosen by a doctor based on level, weight and goal. High doses without monitoring risk overdose. The calculator shows your status but doesn’t prescribe a dose — that’s for a doctor.

  • Yes, with prolonged high doses without monitoring — leading to hypercalcemia (excess calcium). That’s why low levels are corrected under lab monitoring, not by guesswork.

Match vitamin D to your level

Attach your test — AI explains the level and helps pick a vitamin D form and dose for your data (to discuss with a doctor).

Match my vitamin D

This calculator is for reference and information only and is not a diagnosis or prescription. A doctor chooses the replenishment dose; high doses without monitoring are dangerous.