Thorne Vitamin D/K2 Liquid
Best for: a D3 and K2 combination listed in the guide
Vitamin D3 (+K2) Dose Calculator
Use an optional 25(OH)D blood result, goal and body-weight category to compare common vitamin D3 amounts. The estimate is not a prescription.
How to read your result
- Start with Your dose and How to split; this is a comparison point, not a prescription.
- Check the Evidence range / upper limit and safety cautions.
- Weight, age and sex are not dose inputs unless the result explicitly says they are.
Estimate
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Your dose
Enter a valid weight
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How to split
See your serving pattern
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Evidence range / upper limit
Check the method below
Next step
Action
Review the safety notes
Is this based on your weight? Enter a valid weight to see whether this estimate uses it.
Evidence grade B
Medication & safety cautions
- Vitamin K2 can interact with warfarin; do not change vitamin K intake without your prescriber.
- Thiazide diuretics, kidney disease and sarcoidosis can raise concerns about calcium; ask a clinician before supplementing.
How this estimate works
With a 25(OH)D result, the estimate follows the ranges supplied for this tool: below 20 ng/mL: 4,000 IU/day for 8–12 weeks; 20–29: 2,000 IU; 30–50: 1,000 IU; 51–60: 0–600 IU; above 60: no supplement dose and clinician review. Without a result, the base is 1,000 IU below 90 kg or 2,000 IU at/above 90 kg; the specified 1.5 factor at/above 90 kg makes the latter 3,000 IU/day. The cap is 4,000 IU/day. Adults over 70 should account for the 800 IU/day total-intake RDA; this is food plus supplements.
Key studies
- Manson et al. 2019 — New England Journal of Medicine · VITAL trial
- Demay et al. 2024 — Journal of Clinical Endocrinology & Metabolism · Endocrine Society guideline
- Ekwaru et al. 2014 — PLOS ONE · dose response and body weight
Vitamin D buying guide · Intervention evidence
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Life Extension Vitamin D3 5000 IU
Best for: standalone D3 when taking K2 separately
Pure Encapsulations Vitamin D3 5000 IU
Best for: a D3 option listed for people comparing formulations
Frequently asked questions
Should I use a blood test to choose a dose?
A measured 25(OH)D result is more informative than guessing. Discuss repletion doses and follow-up testing with a clinician.
Is this dose based on weight?
Partly. The no-test estimate uses a higher amount above 90 kg, based on the body-weight dose-response literature, and is capped at 4,000 IU/day.
What if I am pregnant or breastfeeding?
The calculator shows the 600 IU/day pregnancy RDA as a reference. Discuss testing and any higher dose with your obstetric clinician.
Educational tool, not medical advice. Check with your doctor, especially if you take medication.