Products · Vitamins & minerals · Kirkland Signature (Costco)
Kirkland Signature Extra Strength D3 50 mcg (2,000 IU)
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Costco’s house-brand vitamin D3 (2,000 IU) at about 2 cents a day, with the USP Verified mark on its label and Costco’s page. USP’s database refused our automated check, so we have not confirmed the listing.
Best for Costco members who want the cheapest vitamin D3 with a recognized certifier’s mark on the label, and who are fine with soybean oil and porcine gelatin.
- Our quality rating
- Fair (3 of 5)
- Price range
- Budget
- Size
- 600 softgels (600 servings); Costco item 393914
approx. $15 for 600 softgels
See it on Kirkland Signature (Costco)’s site →We are not affiliated with Kirkland Signature (Costco). This link goes to the maker’s own page, with no tracking code. How we're funded.
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How we evaluated it
Why we chose it What put it on our list
- The label is plain: one active ingredient, vitamin D3 (cholecalciferol) 50 mcg (2,000 IU) per softgel, half the 4,000 IU upper limit for vitamin D. We read it in the NIH Dietary Supplement Label Database, which holds the Kirkland Signature “D3 50 mcg (2000 IU)” label for item 393914, entered in December 2022.
- The other ingredients are named: soybean oil, gelatin (porcine), glycerin and water in the NIH record, and Costco’s page lists soybean oil, gelatin (porcine), glycerin and vitamin D3. The label says no artificial colors or flavors, and no yeast, starch or gluten.
- Costco’s page lists it as “United States Pharmacopeia (USP) Verified”, and the NIH label record carries the seal “USP Verified Dietary Supplement” with the line “USP has tested and verified ingredients, potency, and manufacturing process.”
- It is the lowest cost per day of the vitamin D3 products we list. Costco.com shows $14.99 for 600 softgels (about 2.5 cents a day), and a $2.50 manufacturer’s savings valid through 15 November 2026 brings it to $12.49.
Trade-offs What to weigh before you buy
- We could not open the USP Verified directory (quality-supplements.org returns “Access Denied” to our tools), so the mark is the maker’s claim for now.
- It is sold in Costco warehouses. Costco.com showed it as unavailable online, and the page says prices vary by warehouse, so the price above is the online listing and a warehouse price may differ.
- The softgel contains soybean oil and porcine gelatin, so it is not for anyone avoiding soy or pork products. The label names Costco as distributor and does not name the manufacturer.
- No certificate of analysis is public. The NIH label record dates from December 2022 and Costco notes that label information from suppliers may change, so read the bottle you buy.
What to know Details worth knowing first
Vitamin D3 is the form most people supplement, and our supplementation guide covers doses and blood testing. This is the cheapest way we have found to take a plain 2,000 IU capsule, if you are a Costco member and the USP mark checks out.
We could read the label in a federal database and on Costco’s page, but not the certifier’s own current listing, which is the part that makes a budget product trustworthy. We are asking about it. For how seals work and what they can and cannot show, see how to tell if a supplement is pure.
Quality & testing How it measures up against our checklist
- Tested by
- USP Verified (claimed on the label and Costco’s page; not confirmed)
- Certificate of analysis
- No
| What we checked | What we found |
|---|---|
| Third-party tested Maker’s claim | Costco’s page and the label (as held in the NIH label database) say USP Verified. USP’s own Kirkland Signature brand page in a 2016 Internet Archive copy listed “Vitamin D3 2000 IU Softgels”, but that is ten years old, and USP’s current directory refused our automated check. |
| A certificate of analysis Not verified | None found on Costco’s page. |
| The right form Maker’s claim | Vitamin D3 (cholecalciferol), 50 mcg (2,000 IU) per softgel, from the NIH label record. Costco’s page shows no supplement facts panel. |
| A plain label Maker’s claim | One active ingredient with an amount; no proprietary blend. |
| Disclosed extras Maker’s claim | Soybean oil, gelatin (porcine), glycerin and water (NIH record). Costco’s page omits the water. Gluten free. |
| Dose against the upper limit Maker’s claim | 2,000 IU against a 4,000 IU upper limit for adults. |
What the labels mean
- Verified We opened an independent record that confirms it: a certifier’s listing, a regulator’s list or a lab report. It is linked under Sources.
- Maker’s claim The maker says so on its own page or label. We read it but found no independent record.
- Not verified We looked and could not confirm it, or the maker does not say. Treat it as unknown.
Sources Where our facts come from
- Costco: Kirkland Signature Extra Strength D3 50 mcg, 600 softgels (item 393914). Maker’s page. Price ($14.99 online, with a $2.50 savings through 15 November 2026), ingredients and the USP Verified statement as seen 2026-10-22. Shown as unavailable online. Open ↗
- NIH Dietary Supplement Label Database: Kirkland Signature D3 50 mcg (2000 IU), label 279473. Independent source. A federal database copy of the label (item 393914, UPC 0 96619 39391 6), entered December 2022. It shows what the label says. It is not a test. Open ↗
- USP Verified brand page for Kirkland Signature (Internet Archive copy, 2 September 2016). Certifier or regulator listing. Ten years old. Lists “Vitamin D3 2000 IU Softgels” among Kirkland Signature’s USP Verified products in 2016. It does not show today’s status. Open ↗
Alternatives Other options to compare
- Nature Made Vitamin D3 2000 IU softgels About $11 for 90, with the USP Verified mark on its label and page. Also unconfirmed.
- Momentous Vitamin D3 2000 IU About $20 for 60, with an NSF listing we opened and public lot certificates.