Best vitamin D, ranked by cost per 1000 IU
Vitamin D3 supplements ranked by $/1000 IU of cholecalciferol, with D3-vs-D2, K2/magnesium cofactor notes, and third-party testing status.
Pure Encapsulations Vitamin D3
D3 (cholecalciferol) in a single-ingredient softgel with a short, hypoallergenic excipient list and per-lot third-party testing. The 5000 IU SKU lands near $0.005 per 1000 IU, which is a defensible mid-tier price for a verified, additive-free formula. The honest caveat: the cholecalciferol itself is chemically identical to what is in a $0.002 generic tablet. The premium buys documented purity and a well-sourced carrier oil, not a better molecule or higher absorption. If excipient sensitivity is not a concern, NOW Foods delivers the same active for less. If you are not yet sure supplementation is worth it, our explainer on what vitamin D does shows the benefit is largest when correcting a measured deficiency.
Every product, ranked.
| # | Notes | Confidence | |||
|---|---|---|---|---|---|
| 01 | NOW Foods Vitamin D-3 | Best $/1000 IU | 01 | D3 (cholecalciferol) in an olive-oil softgel, available 1000-10000 IU. UL-tested and GMP-audited in NOW's own labs. Roughly $0.002 per 1000 IU at the 5000 IU strength. The commodity pick: oil-based delivery, no K2, lowest credible unit cost. | High |
| 02 | Kirkland Signature Vitamin D3 | Best warehouse value | 02 | D3 softgels, typically 2000 IU, in a large Costco count. Around $0.002-0.003 per 1000 IU. USP-verified on most lots. Source documentation is thinner than NOW; buy when the USP mark is on the bottle. | High |
| 03 | Nature Made Vitamin D3 | Best mainstream USP | 03 | D3 (cholecalciferol) softgel, 1000-5000 IU, USP Verified. Oil-based. About $0.004 per 1000 IU. The shelf-presence pick: pharmacy availability plus the USP stamp at near-budget pricing. | High |
| 04 | Doctor's Best Vitamin D3 | Budget oil-based | 04 | D3 in extra-virgin olive oil softgels, 1000-5000 IU. Around $0.003 per 1000 IU. Single ingredient, no K2. Comparable to NOW on price and delivery; choose on whichever is cheaper at purchase. | Medium |
| 05 | NatureWise Vitamin D3 | Mid-tier oil-based | 05 | D3 in organic olive oil, 1000-5000 IU, third-party tested. Roughly $0.006 per 1000 IU. Functionally identical to NOW with heavier marketing; the price gap buys branding, not absorption. | Medium |
| 06 | Pure Encapsulations Vitamin D3 | Best verified-formula | 06 | D3 softgel, 1000-5000 IU, hypoallergenic excipients, per-lot third-party testing. About $0.005 per 1000 IU. The pick for documented purity and excipient sensitivity, not for raw cost. | Medium |
| 07 | Sports Research Vitamin D3 + K2 | Best D3/K2 combo | 07 | 5000 IU D3 plus 100 mcg K2 (MK-7) in coconut oil, Informed-tested. Around $0.008 per 1000 IU before allocating cost to the K2. Reasonable if you want both cofactors in one softgel; redundant if you already eat K2-rich foods or take it separately. | Medium |
| 08 | Thorne Vitamin D + K2 (liquid) | Adjustable-dose clinical | 08 | Liquid D3 (1000 IU/drop) with K2 (MK-4), NSF Certified for Sport. Roughly $0.015 per 1000 IU. Pay the premium for drop-level dose titration and anti-doping certification, not for a better molecule. | Medium |
| 09 | Carlson Vitamin D3 | Premium oil-based | 09 | D3 in softgels, 1000-5000 IU, third-party tested. About $0.01 per 1000 IU. Quality is solid; the unit cost runs several times NOW for the same cholecalciferol. | Medium |
Named, with the reason.
Nordic Naturals Vitamin D3 (in cod liver oil)
Skip for D3 aloneD3 carried in fish oil, 1000 IU per softgel. Around $0.04 per 1000 IU, the priciest in this set per IU. Reasonable only if you want the omega-3s too; a dedicated fish-oil plus a cheap D3 is more cost-efficient.
How this was specified
- 01Inputs measured
- Retail price (dated) · label claim · Certificate of Analysis · third-party test (Informed Sport / NSF / ConsumerLab / Clean Label) · leucine per serving from COA, not marketing.
- 02Protocols tested
- Per-kg target from four literature ranges (IOM RDA, Phillips 2017, Morton 2018, ISSN). Brands scored against Moore 2015 leucine-per-dose threshold (~0.4 g/kg).
- 03Cost-basis verified
- $/gram of protein and $/gram of leucine at warehouse pricing (Costco), mail-order (Amazon), and DTC retail. Re-checked quarterly, flagged when drift exceeds 15%.
- 04Confidence level
- High on ranked order. Medium on absolute $/g (prices drift). Low on serving-size claims where COA is older than 18 months, flagged [VERIFY].
What people ask us most.
- How much vitamin D should I take per day?
- The RDA is 600 IU/day for adults under 70 and 800 IU/day over 70 (IOM 2011), set to maintain bone health in most people. Common maintenance supplementation runs 1000-2000 IU/day, which is what VITAL used (Manson 2019). The tolerable upper intake level (UL) for adults is 4000 IU/day. Doses above the UL should be tied to a measured deficiency and clinician oversight, not taken open-ended.
- Is D3 better than D2?
- Yes, on the metric that matters. Tripkovic 2012's meta-analysis found D3 (cholecalciferol) raises and sustains serum 25(OH)D more effectively than D2 (ergocalciferol) at equivalent doses. D2 is mainly relevant as a prescription high-dose or vegan option. For raising and holding status, choose D3.
- Should I take K2 or magnesium with vitamin D?
- The cofactor case is mechanistic, not proven on hard outcomes. Vitamin K2 directs calcium toward bone via carboxylation, and magnesium is a cofactor in vitamin D metabolism. RCTs showing that adding K2 or magnesium to D3 improves clinical endpoints are limited. If your diet is low in K2-rich foods or you are magnesium-insufficient, a combo product is reasonable; it is not a requirement for D3 to work.
- Do I need a blood test before supplementing?
- It is the only way to dose precisely. The relevant marker is serum 25-hydroxyvitamin D (25-OH-D); a common sufficiency target is 30-50 ng/mL (75-125 nmol/L). Below 20 ng/mL is deficient. A maintenance dose of 1000-2000 IU/day is low-risk without testing, but anyone using higher doses or correcting a suspected deficiency should test, then retest in 8-12 weeks.
- Can you take too much vitamin D?
- Yes. Toxicity is from supplements, not sun, and presents as hypercalcemia. It generally requires sustained intake well above the 4000 IU/day UL, often 10000 IU/day or more for months, pushing 25-OH-D above ~100 ng/mL (NIH ODS). Symptoms include nausea, kidney stones, and in severe cases renal damage. Staying at or below the UL without a measured deficiency keeps the risk near zero.
- Does an oil-based softgel absorb better than a dry capsule or tablet?
- Vitamin D is fat-soluble, so an oil-based softgel has a theoretical absorption edge, and most softgels here use olive, coconut, or fish oil. In practice, the difference is small when a dry tablet is taken with a meal containing fat. The practical rule: take whatever form you own alongside food. Form matters less than consistency.
A published Certificate of Analysis from a ranked brand that contradicts the label claim we scored against. An independent lab result (Clean Label, ConsumerLab) finding heavy-metal or amino-spiking failures on a current top pick. A peer-reviewed meta-analysis that shifts the leucine-per-dose threshold. Any of those triggers a dated revision within a week.
Every claim, cited.
- [01]National Institutes of Health, Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals.
- [02]Tripkovic L et al. 2012. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Am J Clin Nutr 95(6):1357-1364.
- [03]Manson JE et al. 2019. Vitamin D supplements and prevention of cancer and cardiovascular disease (VITAL). N Engl J Med 380(1):33-44.
- [04]Endocrine Society. 2024 Clinical Practice Guideline: Vitamin D for the Prevention of Disease. J Clin Endocrinol Metab.
- [05]Marcinowska-Suchowierska E et al. 2018. Vitamin D toxicity: a clinical perspective. Front Endocrinol 9:550.
The Larderlab Team builds evidence-led frameworks for eating, lifting, and stocking a kitchen. We cite every claim. We publish the spreadsheet when possible. We buy what we review at retail price. When new data lands, we revise with a dated note.
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