Determine your vitamin K requirements for bone health, blood clotting, and cardiovascular protection.
Vitamin K does not get much attention, but it is essential for two things you would not want to go without: helping your blood clot properly (so a small cut stops bleeding) and supporting healthy bones. This calculator estimates your recommended daily amount based on your age and sex, giving you a clear target for a nutrient most people have never thought to track.
There is one important real-world wrinkle with vitamin K that I always mention: if you take a blood-thinning medication like warfarin, your vitamin K intake interacts with it, so consistency matters and you should follow your clinician's guidance rather than making sudden changes.
The name comes from the German word for coagulation, which is a clue to its headline role: vitamin K is essential for blood clotting. Without enough of it, even minor injuries would bleed too easily. It also activates proteins that help bind calcium into your bones, so it works alongside calcium and vitamin D to support bone strength. Two quiet but genuinely vital jobs.
For adults the recommended amount is roughly 90 mcg a day for women and 120 mcg for men. The calculator gives you the figure for your age and sex. These are small amounts, and most people who eat green vegetables reach them without trying, which is part of why deficiency is uncommon in healthy adults.
Leafy green vegetables are by far the best source: kale, spinach, collard greens, broccoli and Brussels sprouts are all loaded with vitamin K. Smaller amounts come from vegetable oils and some fermented foods. A single serving of cooked greens can easily exceed the daily target, so a habit of eating greens a few times a week keeps you well supplied. Because it is fat-soluble, a little fat with your greens aids absorption.
This is the part that matters most for some readers. Blood-thinning medications like warfarin work by interfering with vitamin K, so big swings in how much vitamin K you eat can change how well the medication works. The advice is not to avoid greens, it is to keep your intake steady and predictable, and to talk with your clinician or pharmacist before making major dietary changes. If you are on one of these medications, that conversation is more important than any calculator number.
This calculator uses established, peer-reviewed formulas and reference ranges from recognized health and nutrition authorities. Results are estimates for general education, not a medical diagnosis. For decisions about your health, consult a qualified clinician. Reviewed by Jennifer Zoned, PhD, Nutrition Researcher.
Adults need roughly 90 mcg a day for women and 120 mcg for men. The calculator gives the figure for your age and sex. These are small amounts that most people who eat green vegetables reach easily, which is why deficiency is uncommon in healthy adults.
Leafy greens are the top sources: kale, spinach, collard greens, broccoli and Brussels sprouts are all rich in it. A single serving of cooked greens can exceed the daily target. Eating greens a few times a week, with a little fat to aid absorption, keeps you well supplied.
Yes. Medications like warfarin work by interfering with vitamin K, so large swings in your intake can change how well the medication works. The advice is to keep your vitamin K intake steady rather than avoid greens, and to talk with your clinician or pharmacist before major dietary changes.
It is uncommon in healthy adults who eat a normal diet, because leafy greens supply it easily and the body needs only small amounts. Newborns are an exception and are often given vitamin K at birth, and certain medical conditions affecting fat absorption can raise the risk, which a clinician would manage.
