Is a vitamin D3 label in mcg the same as one in IU?
Our picks, by labeled strength, with a link to buy them: see where to buy. A strength with nothing certified at it has no pick, and is not listed there.
They are the same thing. 62.5 mcg is 2,500 IU. Every one of the 39 panels we have read that prints micrograms uses the same conversion, one microgram to 40 IU, so the two numbers on a vitamin D label are one strength written two ways. 39 of the 52 packages we price print the microgram figure on the panel; the other 13 print IU. That is why the same product can look like two different strengths on two shelves.
Micrograms to IU: 10 mcg is 400 IU; 25 mcg is 1,000 IU; 50 mcg is 2,000 IU; 62.5 mcg is 2,500 IU; 100 mcg is 4,000 IU; 125 mcg is 5,000 IU; 250 mcg is 10,000 IU; 1,250 mcg is 50,000 IU. IU to micrograms: 400 IU is 10 mcg; 500 IU is 12.5 mcg; 1,000 IU is 25 mcg; 2,000 IU is 50 mcg; 5,000 IU is 125 mcg; 10,000 IU is 250 mcg; 50,000 IU is 1,250 mcg. Divide IU by 40 for micrograms, or multiply micrograms by 40 for IU.
Which strength to take is not a question this page answers or has any business answering. 1,000 IU is only the unit this site prices vitamin D against, so that packages of different strengths can be compared at all.
| On the panel | The same in IU | Packages | Cheapest per 1,000 IU | Cheapest at this strength |
|---|---|---|---|---|
| 25 mcg on some, IU on the rest | 1,000 IU | 11 | $0.044 | Sports Research Vitamin D3 1,000 IU (360 softgels) buy |
| 50 mcg on some, IU on the rest | 2,000 IU | 8 | $0.025 | Sports Research Vitamin D3 2,000 IU (360 softgels) buy |
| 62.5 mcg | 2,500 IU | 2 | $0.018 | BulkSupplements.com Vitamin D3 2,500 IU Softgels (500 count) buy |
| 100 mcg | 4,000 IU | 2 | $0.012 | Sports Research Vitamin D3 4,000 IU (360 softgels) buy |
| 125 mcg on some, IU on the rest | 5,000 IU | 18 | $0.01 | Micro Ingredients Vitamin D3 5,000 IU (500 softgels) buy |
| 250 mcg on some, IU on the rest | 10,000 IU | 8 | $0.004 | BulkSupplements.com Vitamin D3 10,000 IU Softgels (500 count) buy |
| 1,250 mcg on some, IU on the rest | 50,000 IU | 3 | $0.001 | BulkSupplements.com Vitamin D3 50,000 IU Softgels (365 count) buy |
Both figures come from each product's own Supplement Facts panel, and the product page names the source for each one. Where a panel prints only one of the two, the other is the conversion above, and a row holding both kinds of label says so rather than showing one figure for all of them. What each strength costs, ranked inside the strength, is on the cheapest vitamin D3 page.
Where to buy: the picks, by labeled strength
The pick is the cheapest certified product, at the exact package sold where the certifier names packages, with no adverse finding on record, a price its retailer let us read recently, and no more than a year’s supply at the label’s serving; per delivered dose where the retailer publishes a delivery rate. Where none does, it is the cheapest such product before delivery, and it says how far the order is from free delivery. It is the same pick the category page shows.
How these lines are chosen
Among 10 products and 10 retailer listings we track; Amazon and Walmart are not included. A month is thirty doses of the size in the heading, priced the same way as the per-dose figure beside it. “Delivery known” ranks only products whose retailer publishes a delivery rate; a cheaper product with an unpublished rate is on its own line, or in the full list below.
How these lines are chosen
Among 6 products and 6 retailer listings we track; Amazon and Walmart are not included. A month is thirty doses of the size in the heading, priced the same way as the per-dose figure beside it. “Delivery known” ranks only products whose retailer publishes a delivery rate; a cheaper product with an unpublished rate is on its own line, or in the full list below.
How these lines are chosen
Among 11 products and 11 retailer listings we track; Amazon and Walmart are not included. A month is thirty doses of the size in the heading, priced the same way as the per-dose figure beside it. “Delivery known” ranks only products whose retailer publishes a delivery rate; a cheaper product with an unpublished rate is on its own line, or in the full list below.
How these lines are chosen
Among 2 products and 2 retailer listings we track; Amazon and Walmart are not included. A month is thirty doses of the size in the heading, priced the same way as the per-dose figure beside it. “Delivery known” ranks only products whose retailer publishes a delivery rate; a cheaper product with an unpublished rate is on its own line, or in the full list below. No product here publishes a delivery rate below its free-delivery threshold, so the pick is priced before delivery.
Full comparison of every product in this category: Vitamin D3. Every question we answer: the question index.
What this rests on: prices we last recorded at the retailer named on each product page, which go stale, and each page says when it was checked; the products we track, not every product sold, and Amazon and Walmart are not among the stores; listings and labels read at the source, each linked from the page. Found an error? Tell us. The full method: How we compare.