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Best value vitamin D in Australia: how to compare cost per dose

This page hasn't been reviewed by a pharmacist yet. It's general information, not medical advice.

Short answer

The cheapest bottle is often not the best value. Compare vitamin D products on cost per day at the dose on the label: divide the price by the number of doses, and convert micrograms to IU (1 µg = 40 IU) so you compare like with like. Ask your doctor whether you need a supplement at all; healthdirect suggests a blood test conversation if you're concerned. Don't go above the 80 µg (3,200 IU) adult upper limit without medical advice.

Step 1: put every label in the same unit

Labels use micrograms (µg) or international units (IU). NIH ODS gives the conversion: 1 µg of vitamin D equals 40 IU. [1] So 25 µg = 1,000 IU and 50 µg = 2,000 IU.

Step 2: work out cost per daily dose

Cost per day = price ÷ number of daily doses in the pack. If one tablet is 1,000 IU and you're comparing it with a 5,000 IU tablet, compare cost per 1,000 IU, not per tablet. Write down the date and retailer when you check; prices change often.

Step 3: check the dose is sensible for you

The Australian/NZ adult upper level of intake for vitamin D is 80 µg/day (3,200 IU). [2] A higher-strength product that looks cheaper per IU isn't good value if the dose is more than you should take. healthdirect says if your doctor finds you're low, you might need a supplement, and to speak with your doctor, pharmacist or dietitian first. [3]

Step 4: D3 vs D2 and the form

healthdirect explains vitamin D comes as D2 (ergocalciferol) and D3 (cholecalciferol). [3] NIH ODS summarises research comparing the two forms. [1] Capsule, tablet, liquid and spray forms differ in price, so compare at the same dose.

Step 5: count every source

Vitamin D is also in many multivitamins, calcium products and some fortified foods. [3] Add them up before buying a standalone product.

FAQ

Is a higher IU vitamin D better value?

Only if you need that dose. Compare cost per 1,000 IU at a dose your doctor agrees with, and stay within the 3,200 IU/day adult upper limit unless advised otherwise.

How do I convert µg to IU?

Multiply micrograms by 40. For example, 25 µg = 1,000 IU.

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Related

Sources

  1. NIH ODS: Vitamin D fact sheet for health professionals
  2. NHMRC Nutrient Reference Values: Vitamin D
  3. healthdirect: Vitamin D and your health

Sources checked 2026-10-18. Last updated 2026-10-18.