Vitamin K2 (MK-7): dose, why it pairs with D3, and cost

Vitamin K2 is commonly taken as 90-180 mcg/day of MK-7, and it is often paired with vitamin D3 because the two work together on calcium. When you buy it, compare by cost per mcg of MK-7, not per capsule. And one warning up front: if you take warfarin, do not add K2 without talking to your clinician first.

What vitamin K2 does

Vitamin K2's best-understood job is helping the body put calcium where it belongs. It activates proteins that direct calcium into bone and help keep it out of soft tissue like artery walls. That is the core idea behind supplementing it: not just having enough calcium, but routing it well.

This is also why K2 rarely travels alone.

Why K2 pairs with D3

Vitamin D3 and K2 are complementary:

• Vitamin D3 raises how much calcium you absorb from food.
• Vitamin K2 helps route that calcium toward bone and away from arteries.

Taken together, the logic is that D3 brings more calcium into the system and K2 helps it end up in the right place. That is why so many products combine them, and why people building a bone-support routine often consider them as a pair. For the combined approach, see /guides/vitamin-d3-k2-together. This is general information, not medical advice.

MK-7 vs MK-4

Vitamin K2 comes in two supplemental forms, and they are not interchangeable dose-for-dose:

• MK-7 is the longer-lasting form. It stays in circulation longer, is dosed in micrograms (typically 90-180 mcg), and is the most common form in supplements.
• MK-4 clears from the body much faster and is therefore used at much higher doses.

For everyday supplementation, MK-7 is the usual choice precisely because its longer half-life means a small daily microgram dose can keep levels steady. If you are comparing products, most of what you will see — and what these dose figures refer to — is MK-7.

The dose

A common range is:

• 90-180 mcg/day of MK-7.
• Taken with a meal containing fat, since K2 is fat-soluble and absorbs better that way.

Follow the specific product's label. If your K2 is bundled with D3, check both amounts so you know what you are actually taking of each. This is general information, not medical advice.

The warfarin warning — read this

This is the most important safety point on the page. Vitamin K interacts with warfarin, a common blood thinner. Warfarin works precisely by blocking vitamin K, so adding a K2 supplement can work against the medication and change how well it controls clotting.

• If you take warfarin (or another vitamin-K-antagonist blood thinner), do not start K2 on your own.
• Talk to the clinician who manages your medication first — consistency of vitamin K intake matters for these drugs.

This is not a form-of-K2 loophole; it applies to vitamin K generally. Not medical advice.

The label details that matter

Before buying, check:

• The form and amount — confirm it is MK-7 and note the mcg per serving.
• Whether D3 is included, and at what dose, if you want the pair.
• Third-party testing where available.

Because strengths vary a lot between products, the front-label capsule count tells you little about value on its own.

How to buy vitamin K2 by cost per dose

Do not compare K2 bottles by price per capsule — MK-7 strength differs widely, so that number misleads. Instead:

• Compare by cost per mcg of MK-7.
• Divide the total price by the total MK-7 delivered, or by the number of doses at your target strength (say 90-180 mcg).
• If you are buying a D3+K2 combo, make sure both doses match what you actually want before comparing on price.

Compare current prices per dose on /nutrients/vitamin-k2, see the best current value picks on /best/vitamin-k2, and read exactly how we calculate cost per dose on /methodology.

Buy the MK-7 option with the lowest cost per mcg, pair it with D3 if that fits your goal, and clear it with a clinician first if you are on warfarin.