Vitamin B12 Requirement Calculator

Work out vitamin b12 requirement instantly with clear inputs, formula shown and shareable results.

About Vitamin B12 Requirement Calculator

Applies the life-stage vitamin B12 reference intakes and flags the situations where fortified foods or supplements are needed rather than diet alone.

Formula

Vitamin B12 reference intakes

2.4 microg/day for adults, 2.6 in pregnancy and 2.8 while breastfeeding; higher supplemental doses are used because passive absorption is inefficient

Worked example

With the default values below, Vitamin B12 Requirement Calculator returns Vitamin B12 requirement of 2.40. Change any input above and every figure here is recalculated in your browser.

Inputs used

Life stageone of Adult, Pregnancy, Breastfeeding, Over 50: Adult
Dietone of Mixed diet, Vegetarian, Vegan: Mixed diet

Results

Vitamin B12 requirement: 2.40 microg/day
Suggested supplemental dose: 0.0 microg/day
Dietary source note: Animal foods normally cover the requirement
Absorption note: Food-bound absorption is normally adequate

Step by step

1Values used
2Vitamin B12 reference intakes
3Vitamin B12 requirement= 2.40 microg/day
4Suggested supplemental dose= 0.0 microg/day
5Dietary source note= Animal foods normally cover the requirement
6Absorption note= Food-bound absorption is normally adequate

Assumptions and limits

The result is derived only from the 2 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 are supplement doses so much larger?

Only about 1% of a large oral dose is absorbed passively once the intrinsic factor route saturates at about 1.5 microg per meal.

How long do stores last?

Liver stores can cover two to five years, which is why vegan deficiency often appears only after a long delay.