Vitamin D Calculator
Dose to reach a target blood level.
Enter your values
ⓘ Live results
Results
- Suggested daily dose
- 6,100 IU
- Level gap to close
- 22 ng/mL
- Target in nmol/L
- 100
- Current status
- Deficient
- Time to steady state
- 8–12 weeks
Quick answer
Each 1000 IU of daily vitamin D3 raises serum 25(OH)D by roughly 10 nmol/L (4 ng/mL) at steady state.
How to use the Vitamin D Calculator
- 1Enter your current 25(OH)D blood level.
- 2Enter your target level (30–50 ng/mL is typical).
- 3Enter body weight for dose adjustment.
Worked example
Using the values the calculator loads with:
Inputs
- Current 25(OH)D18 ng/mL
- Target level40 ng/mL
- Body weight78 kg
Results
- Suggested daily dose6,100 IU
- Level gap to close22 ng/mL
- Target in nmol/L100
- Current statusDeficient
- Time to steady state8–12 weeks
Frequently asked questions
What is the safe upper limit?
4000 IU a day for most adults without medical supervision.
Should I retest?
Yes, after about three months of consistent supplementation.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.