Vitamin D Dose Calculator

Work out vitamin d dose instantly with clear inputs, formula shown and shareable results.

About Vitamin D Dose Calculator

Uses the widely cited relationship that 100 IU of vitamin D3 daily raises 25-hydroxyvitamin D by about 1 ng/mL, and adds a weight-adjusted maintenance dose.

Formula

Vitamin D repletion

Daily dose (IU) = (target - current level in ng/mL) x 100; maintenance is 1,000 to 2,000 IU/day, higher in obesity

Worked example

With the default values below, Vitamin D Dose Calculator returns Daily supplemental dose to close the gap of 800. Change any input above and every figure here is recalculated in your browser.

Inputs used

Current 25-hydroxyvitamin Daccepts 2–80 ng/mL: 22 ng/mL
Target levelaccepts 20–60 ng/mL: 30 ng/mL
Weightaccepts 20–250 kg: 70 kg

Results

Daily supplemental dose to close the gap: 800 IU
Maintenance dose: 1,000 IU/day
Gap to the target level: 8.00 ng/mL
Weeks before rechecking the level: 12 weeks

Step by step

1Values used
2Vitamin D repletion
3Daily supplemental dose to close the gap= 800 IU
4Maintenance dose= 1,000 IU/day
5Gap to the target level= 8.00 ng/mL
6Weeks before rechecking the level= 12 weeks

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

Why does obesity raise the requirement?

Vitamin D is sequestered in adipose tissue, so a larger dose is needed for the same serum rise.

What is the upper limit?

4,000 IU a day is the tolerable upper intake level for adults; higher doses are used only under supervision.