Dosing a D3-K2 product does not begin with the largest figure on the package. Check the units, amount per drop or capsule and the actual reason for use. Vitamins D and K have different functions; their combination does not provide a personal dosing formula.
Micrograms and International Units
For vitamin D, 1 microgram equals 40 International Units, or IU. This conversion expresses the same vitamin D amount in two units. It must not be applied to vitamin K2. [1]
| Amount | Conversion | Meaning |
|---|---|---|
| 1 µg vitamin D | 40 IU | A unit conversion only |
| 20 µg vitamin D | 800 IU | DGE guidance when the body's own production is absent or insufficient |
| 100 µg vitamin D | 4,000 IU | Tolerable total daily intake for adults, not an intake target |
| K2 declared in µg | The D3 conversion does not apply | Consider this nutrient and the medicine plan separately |
Distinguish reference values, upper limits and treatment
The German Nutrition Society specifies 20 micrograms daily as supplementation for adults when endogenous vitamin D production is absent or insufficient. The tolerable total intake of 100 micrograms includes all foods and supplements. It is not an instruction to consume that amount daily. Medically justified treatments require separate clinical planning. [1]
A hypothetical label example: if one drop contains 1,000 IU, two drops provide 2,000 IU, or 50 micrograms. This is a calculation, not a recommendation. When changing brands, do not automatically retain the previous number of drops.
Why K2 is not an automatic safety addition
Vitamin K participates in blood clotting and bone metabolism, among other functions. This does not mean everyone must add the same K2 amount to every vitamin D dose. With vitamin-K antagonists such as warfarin, changing vitamin K intake can affect treatment. Do not start or alter K2 without coordinating with the treating team. [2]
High vitamin D intake can raise blood calcium and cause harm. A combination label does not remove this risk. [3] Do not justify a self-selected high dose by pointing to added K2.
Make total intake visible
List every product containing vitamin D or K, including multivitamins. Record amount per unit and frequency separately. A daily product and a medically prescribed intermittent preparation must not accidentally be used on the same schedule.
When you have a prescription, discuss changes with the treating practice. Whether and when blood tests are needed depends on the circumstances; an arbitrary desired number from the internet is not a universal treatment target.
Frequently asked questions
How many IU equal 20 micrograms of vitamin D?
800 IU. This is not a K2 conversion.
Are 4,000 IU a standard daily recommendation?
No. The stated upper limit is not a general intake target.
Does every vitamin D intake automatically require K2?
A universal supplementation requirement cannot be inferred from metabolic functions.
Can I add K2 myself while taking anticoagulants?
With vitamin-K antagonists, this must be coordinated with the treating team.
Further reading
Assessing D3, K2 and magnesium as a combination and recognizing overlapping intake from combination supplements.
Sources
- German Nutrition Society: Supplements, vitamin D section
- NIH ODS: Vitamin K
- MedlinePlus: Hypervitaminosis D
Editorially updated: September 28, 2026. Information for adults, not individual dosing or deficiency treatment.
