Is Kirkland Signature Worth It? Every Label, Graded
Not medical advice. This grades Costco’s house brand on the labels it files with the NIH, the USP Verified mark, and the absorption trials behind the fish oil. Prices are Amazon reseller prices; Costco warehouse prices are lower and we do not print numbers we cannot verify live. We have no relationship with Costco.
Quick answer
Kirkland Signature is the most-verified house brand in the country and its most famous product is its weakest. Of the 44 Kirkland Signature supplement labels filed with the NIH, 31 (70.5%) carry the USP Verified mark, a rate only Nature Made matches (78% of 18 tracked products; NOW Foods 0%). The fish oil is USP Verified too, and it is 57% omega-3 as ethyl esters, the form absorbed at 73% of natural fish oil; the Amazon version carries 300 mg of omega-3 in a 1,000 mg softgel.
Buy the verified basics at Costco: vitamin D3, CoQ10, the multivitamin, calcium, glucosamine. Skip the fish oil unless you will take three with a fatty meal, and skip the gummies. 13 labels state no USP mark, and gummies are 75% verified against 70% of the rest. See all 44 labels →
The USP rate: what Kirkland gets right
Original researchEvery on-market label filed under the brand Kirkland Signature in the NIH Dietary Supplement Label Database on 2026-09-18: 44 labels, read in full for form, serving, Supplement Facts rows and every statement on the pack. USP Verified = the label itself states the mark.
The USP Verified mark is the one third-party program that tests a finished supplement for identity, potency against the label, purity (heavy metals, microbes, pesticides) and dissolution, and audits the factory. Most brands never submit a product. Kirkland submits nearly its whole line: 31 of 44 labels state the mark, and among the tablets and softgels that make up the core range the rate is 70%. In our own catalog the comparison is stark: Nature Made, the brand built on the USP program, is at 78% across 18 tracked products; NOW Foods, the widest catalog we cover, at 0% across 105; Nature’s Bounty at 0% of 20. The Nature Made report card has the same computation for that brand.
| Item | Value (%) |
|---|---|
| Kirkland Signature (44 filed labels) | 70.5% |
| Nature Made (18 tracked) | 78% |
| Nature's Bounty (20 tracked) | 0% |
| NOW Foods (105 tracked) | 0% |
The mark tells you the capsule contains what the label says and dissolves; it does not tell you the dose is right for you or that the form is the best one. That is where Kirkland’s line has real gaps, and the fish oil is the first.
How we read the labels, and what did not hold
Method: 44 on-market labels returned by the NIH Dietary Supplement Label Database for the brand “Kirkland Signature” on 2026-09-18, read in full. This is a complete enumeration of the filed line, not a sample, so the split-half check is a consistency check rather than a sampling test: 2 of 4 shares agreed across halves (not printed: tablet share; softgel share). Brand comparison rates are computed live from our catalog’s certification field and cover only the products we track for those brands. What it cannot tell you: Costco warehouse prices, products Costco sells that have not been filed with the NIH, or whether a reseller’s stock is the current lot.
The fish oil: verified, cheap, and 57% omega-3 as ethyl esters
The Kirkland fish oil label on file with the NIH, Fish Oil 1200 mg, is a 1,200 mg softgel delivering 684 mg of total omega-3 fatty acids as ethyl esters, two rows of 410 and 274 mg, one softgel a day. The version sold on Amazon, Kirkland Signature Omega-3 Fish Oil Concentrate 1000 mg, is lower still: 300 mg of omega-3 in a 1,000 mg softgel, 30% concentration, against 750 mg in one NOW Foods Ultra Omega-3 softgel or 950 mg in one Sports Research Triple Strength Omega-3. To match one concentrated softgel you take 2.5 Kirkland softgels.
The form matters as much as the concentration. In a 72-volunteer comparison of concentrated fish oil formulations at the same EPA+DHA dose, bioavailability from ethyl esters was 73% of natural fish oil and from re-esterified triglycerides 124% (Dyerberg 2010, PMID 20638827). Ethyl esters need a fatty meal: in a crossover study of 54 adults, a prescription ethyl-ester omega-3 taken with a low-fat meal delivered a quarter of the EPA+DHA that a free-fatty-acid formulation did, and the gap narrowed to 1.3× with a high-fat meal (Davidson 2012, PMID 23312053). A dilute ethyl-ester softgel taken with breakfast cereal is the worst case on both counts. The omega-3 forms comparison ranks the alternatives.
| Fish oil | Per 1,000 mg omega-3 | Omega-3 / serving | Servings | Price | Certification | Buy |
|---|---|---|---|---|---|---|
| NOW Foods Ultra Omega-3 | $0.21 | 750 mg | 180 | $28.94 | none stated | Check price |
| Kirkland Signature Omega-3 Fish Oil Concentrate 1000 mg | $0.28 | 300 mg | 400 | $34.00 | USP Verified (per Costco label) | Check price |
| Viva Naturals Triple Strength Omega-3 | $0.30 | 2,070 mg | 90 | $55.96 | IFOS 5-Star | Check price |
| Sports Research Triple Strength Omega-3 | $0.34 | 950 mg | 90 | $28.87 | IFOS 5-Star, MSC Certified | Check price |
| Carlson Elite Omega-3 Gems | $0.47 | 1,400 mg | 65 | $42.42 | IFOS 5-Star | Check price |
| Nordic Naturals Ultimate Omega | $0.63 | 1,100 mg | 90 | $62.00 | IFOS 5-Star | Check price |
| Nordic Naturals Algae Omega | $1.21 | 585 mg | 60 | $42.49 | Certified Vegan | Check price |
At the Amazon reseller price Kirkland’s fish oil is $0.28 per 1,000 mg of omega-3, rank 2 of 7; it carries the lowest omega-3 per softgel of any fish oil we track. At the warehouse price it would move up the table, and the concentration and the ethyl-ester form would not.
What to buy at Costco
Product links go to Amazon resellers and we may earn a commission if you buy. It never changes which product we pick or what we say about it; the same items are cheaper in a Costco warehouse. How we choose.
What to skip, and why
The fish oil, for the reasons above, unless you will take 2.5 softgels with the fattiest meal of the day. The gummies: only 75% of Kirkland’s gummy labels carry the USP mark against 70% of the rest of the line, and the calcium gummies (Kirkland Signature Calcium 500 mg with D3 Adult Gummies) deliver 500 mg of calcium with 3 g of added sugar in two gummies, which the calcium ranking shows a tablet does without the sugar. The unverified specialty lines: krill oil (120 mg of omega-3 per softgel), ubiquinol, turmeric and the UC-II joint formula state no USP mark, and the Kirkland premium on those is only the Costco price. Magnesium: the filed label is magnesium citrate, 250 mg per two softgels, not verified; the cheapest glycinate ranking gets you a better-absorbed form for a similar price per milligram.
All 44 Kirkland Signature labels filed with the NIH
| Label | Form | Serving | Main rows | USP Verified | Filed |
|---|---|---|---|---|---|
| Active Vitamin Pack | Other | 1 Packet(s) | Vitamin A 2500 IU; Vitamin C 590 mg; Vitamin D3 500 IU | yes | 2019 |
| Adult Multivitamin Gummies | Gummy | 2 Gummie(s) | Vitamin A 750 mcg; Vitamin C 30 mg; Vitamin D 20 mcg | yes | 2020 |
| B12 5000 mcg Cherry Flavor | Tablet | 1 Tablet(s) | Vitamin B12 5000 mcg | yes | 2022 |
| C 1000 mg | Tablet | 1 Tablet(s) | Vitamin C 1000 mg; Citrus Bioflavonoid Complex 100 mg | yes | 2022 |
| C 250 mg Tangerine | Gummy | 2 Gummie(s) | Vitamin C 250 mg | yes | 2020 |
| Calcium 500 mg with D3 Adult Gummies | Gummy | 2 Gummy(ies) | Vitamin D 25 mcg; Calcium 500 mg; Phosphorus 230 mg | yes | 2020 |
| Calcium 600 mg | Tablet | 1 Tablet(s) | Vitamin D3 10 mcg; Calcium 600 mg | yes | 2022 |
| Calcium 600 mg + D3 | Tablet | 1 Tablet(s) | Vitamin D 400 IU; Calcium 600 mg | yes | 2019 |
| Calcium 600 mg with Vitamin D3 | Tablet | 1 Tablet(s) | Vitamin D3 10 mcg; Calcium 600 mg | yes | 2022 |
| Calcium 600 mg with Vitamin D3 | Tablet | 1 Tablet(s) | Vitamin D3 10 mcg; Calcium 600 mg | yes | 2023 |
| Calcium Chews Chocolate Flavored | Other | 1 Piece(s) | Vitamin D 200 IU; Vitamin K 40 mcg; Calcium 500 mg | no | 2019 |
| Calcium Citrate Magnesium and Zinc | Tablet | 2 Tablet(s) | Vitamin D3 20 mcg; Vitamin B6 10 mg; Calcium 500 mg | yes | 2017 |
| Calcium Citrate with 500 mg of Calcium | Tablet | 2 Tablet(s) | Vitamin D3 800 IU; Vitamin B6 10 mg; Calcium 500 mg | yes | 2013 |
| Chewable C 500 mg Tangy Orange Taste | Tablet | 1 Tablet(s) | Vitamin C 500 mg | yes | 2022 |
| Chewable Vitamin C 500 mg Tangy Orange | Tablet | 1 Tablet(s) | Vitamin C 500 mg | yes | 2019 |
| CoQ10 300 mg | Softgel | 1 Softgel(s) | Coenzyme Q10 300 mg | yes | 2019 |
| D3 50 mcg (2000 IU) | Softgel | 1 Soft Gel(s) | Vitamin D3 50 mcg | yes | 2022 |
| Daily Multi Vitamins & Minerals | Tablet | 1 Tablet(s) | Vitamin A 3500 IU; Vitamin C 90 mg; Vitamin D3 400 IU | yes | 2013 |
| E 180 mg (400 IU) | Softgel | 1 Softgel(s) | Vitamin E 180 mg | yes | 2023 |
| Energy B-Complex Adult Gummies | Gummy | 2 Gummie(s) | Vitamin B1 0.15 mg; Vitamin B2 3 mg; Vitamin B6 3.5 mg | no | 2017 |
| Extra Strength Glucosamine 1500 mg Chondroitin 1200 mg | Tablet | 2 Tablet(s) | Glucosamine Hydrochloride 1500 mg; Chondroitin Sulfate Sodium 1200 mg | yes | 2022 |
| Extra Strength Glucosamine 1500 mg Chondroitin 1200 mg | Tablet | 2 Tablet(s) | Glucosamine Hydrochloride 1.5 Gram(s); Chondroitin Sulfate Sodium 1.2 Gram(s) | yes | 2019 |
| Extra Strength Glucosamine HCl 1500 mg with MSM 1500 mg | Tablet | 2 Tablet(s) | Glucosamine Hydrochloride 1500 mg; Methyl Sulfonyl Methane 1500 mg | yes | 2022 |
| Extra Strength Vitamin D3 2000 IU | Softgel | 1 Softgel(s) | Vitamin D3 2000 IU | yes | 2016 |
| Fast Acting Lactase | Other | 1 Caplet(s) | Lactase 0 NP | no | 2016 |
| Fiber Capsules | Capsule | 2 Capsule(s) | Soluble Fiber 2 Gram(s); Iron 0.4 mg; Potassium 30 mg | no | 2019 |
| Fish Oil 1200 mg | Softgel | 1 Softgel(s) | Fish Oil 1200 mg; Docosahexaenoic Acid Ethyl Ester 410 mg; Docosahexaenoic Acid Ethyl Ester 274 mg | yes | 2019 |
| Glucosamine 1500 mg Chondroitin 1200 mg | Tablet | 2 Tablet(s) | Glucosamine HCl 1.5 Gram(s); Chondroitin Sulfate Sodium 1.2 Gram(s) | yes | 2013 |
| Glucosamine HCl 1500 mg with MSM 1500 mg | Tablet | 2 Tablet(s) | Glucosamine HCl 1500 mg; MSM 1500 mg | yes | 2013 |
| Hair, Skin & Nails Strawberry Cream Flavored Coating | Tablet | 2 Tablet(s) | Vitamin A 5000 IU; Vitamin C 60 mg; Vitamin D3 1000 IU | no | 2019 |
| Krill Oil 500 mg | Softgel | 1 Softgel(s) | Krill Oil 500 mg; Omega-3 Fatty Acids 120 mg; Eicosapentaenoic Acid 60 mg | no | 2019 |
| Magnesium Citrate 250 mg | Softgel | 2 Softgel(s) | Magnesium Citrate 125 mg | no | 2019 |
| Ocusight Adult 50+ | Softgel | 1 Softgel(s) | Vitamin C 150 mg; Vitamin E 20.1 mg; Zinc 9 mg | no | 2020 |
| Optifiber | Powder | 2 Teaspoon(s) | Soluble Fiber 3 Gram(s) | yes | 2022 |
| Optifiber | Powder | 2 tsp | Soluble Fiber 3 Gram(s) | no | 2017 |
| Organic Multivitamin | Tablet | 1 Tablet(s) | Vitamin A 945 mcg RAE; Vitamin C 90 mg; Vitamin D3 30 mcg | yes | 2022 |
| Performance Multi Energy Formula | Tablet | 1 Tablet(s) | Vitamin A 5000 IU; Vitamin C 120 mg; Vitamin D3 400 IU | yes | 2019 |
| Sugar Free Children's chewable | Tablet | 0.5 Tablet(s) | Vitamin A 1250 IU; Vitamin C 125 mg; Vitamin D3 200 IU | yes | 2013 |
| Super B-Complex With Electrolytes | Tablet | 1 Tablet(s) | Vitamin C 200 mg; Thiamine 100 mg; Riboflavin 20 mg | yes | 2016 |
| Super B-Complex with Electrolytes | Tablet | 1 Tablet(s) | Vitamin C 200 mg; Thiamine 100 mg; Riboflavin 20 mg | yes | 2022 |
| Triple Action Joint Health | Tablet | 1 Tablet(s) | UC-II Proprietary Cartilage Blend 40 mg; undenatured Type II Collagen 0 NP; Boron Glycinate 5 mg | no | 2020 |
| Turmeric 1000 mg | Capsule | 2 Capsule(s) | Turmeric Root Extract 1000 mg; Black Pepper Fruit Extract 10 mg | no | 2023 |
| Ubiquinol 200 mg | Softgel | 1 Softgel(s) | Vitamin E 30 IU; Kaneka Ubiquinol 200 mg | no | 2020 |
| Ultra Strength Antacid Calcium Carbonate 1000 mg Assorted Berry Flavors | Tablet | 2 Tablet(s) | Calcium 800 mg | no | 2019 |
Frequently asked questions
Are Kirkland Signature supplements good quality?
On the measure that can be checked, yes: 31 of the 44 Kirkland Signature supplement labels filed with the NIH carry the USP Verified mark (70.5%), which means USP tested the product's potency, purity and dissolution against its label. Among the brands in our catalog only Nature Made runs a comparable rate (78% of 18 tracked products); NOW Foods is at 0%. The 13 Kirkland labels without the mark are mostly gummies, chews, fiber and the krill, ubiquinol and turmeric lines.
Is Kirkland fish oil any good?
It is verified and it is dilute. The Costco-shelf label filed with the NIH, Fish Oil 1,200 mg, delivers 684 mg of omega-3 per softgel as ethyl esters (57% concentration), and the version sold on Amazon is 1,000 mg fish oil with 300 mg omega-3, 30%. Ethyl-ester fish oil was absorbed at 73% of natural fish oil in a 72-person comparison, against 124% for re-esterified triglycerides, so you need more softgels and a fatty meal. Per 1,000 mg of omega-3 the Amazon-priced Kirkland ranks 2 of 7 fish oils we track; at the warehouse price it is cheaper than that.
Is Kirkland vitamin D3 the same as Nature Made?
Both are 2,000 IU cholecalciferol softgels in soybean oil and both carry USP Verified on the label. Kirkland's NIH filing is D3 50 mcg (2,000 IU), one softgel a day, USP Verified; Nature Made's 2,000 IU is the same dose and mark. On Amazon Kirkland costs $0.021 a softgel in a five-bottle pack against $0.050 for Nature Made; at the Costco warehouse the Kirkland bottle is cheaper still. There is no reason to pay more for either.
Which Kirkland supplements are not USP Verified?
13 of the 44 filed labels state no USP mark: Calcium Chews Chocolate Flavored; Energy B-Complex Adult Gummies; Fast Acting Lactase; Fiber Capsules; Hair, Skin & Nails Strawberry Cream Flavored Coating; Krill Oil 500 mg; Magnesium Citrate 250 mg; Ocusight Adult 50+; Optifiber and 4 more. Gummies are the weak spot (75% of Kirkland's gummy labels carry the mark against 70% of everything else), and the specialty lines (krill oil, ubiquinol, turmeric, the UC-II joint formula) are not verified.
Is Kirkland CoQ10 worth it?
Kirkland CoQ10 300 mg is ubiquinone in soybean oil, USP Verified, one softgel a day. At the Amazon price it is $0.083 per 100 mg, rank 1 of 6 CoQ10 products we track; the Costco price is lower. The 300 mg dose is at the top of the trialled range for statin muscle symptoms and heart failure, so one softgel covers most protocols. The Kirkland Ubiquinol 200 mg, the reduced form, is not USP Verified.
Can I buy Kirkland supplements without a Costco membership?
Yes, through Amazon and other resellers, at a markup: the prices on this page are Amazon reseller prices for multi-packs, which is why a Kirkland product can rank mid-table here and still be the cheapest option on a Costco shelf. Costco.com also sells the line to non-members with a surcharge. Check that the reseller listing shows the USP mark and a lot number; the label filed with the NIH is the reference.
Related guides
- Supplement brand report cards
- Is Nature Made worth it?
- Best fish oil, ranked
- Omega-3 forms compared
- Best vitamin D supplement
- CoQ10: ubiquinone vs ubiquinol and dose
- Best multivitamin
Sources
- Dyerberg J, et al. “Bioavailability of marine n-3 fatty acid formulations.” Prostaglandins Leukot Essent Fatty Acids. 2010. PMID: 20638827
- Davidson MH, et al. “A novel omega-3 free fatty acid formulation has dramatically improved bioavailability during a low-fat diet compared with omega-3-acid ethyl esters: the ECLIPSE study.” J Clin Lipidol. 2012. PMID: 23312053
- US Pharmacopeia. USP Verified Mark program requirements. usp.org
- NIH Office of Dietary Supplements. Dietary Supplement Label Database, brand “Kirkland Signature”, 44 on-market labels. dsld.od.nih.gov (retrieved 2026-09-18).