According to this site, 1 IU (international units) of retinol = 0.3 micrograms of retinol. Therefore, 2500 IUs = 750 micrograms or 0.750 grams of retinol.

I assume this is the amount in one tube which has a net volume of 40 mls. Assuming the specific gravity of the cream is about 1.0 (which is close enough) the percentage of retinol in the product is 0.75 gr retinol/40 gr product = 0.01875gr retinol/gr product = 1.875% retinol.

TKS a lot Randy. But why when I use an online conversion the results for 750 micrograms is 0.00075g? I guess I was doing something wrong because my results were too low.

Because I'm an IDIOT! I read "micrograms" but did the conversion for "milligrams." Thanks for catching my stupid mistake!

So it should be:

0.00075 gr retinol/40 gr product = 0.00001875gr retinol/gr product = 0.001875% % retinol.

That seems WAY to low to be effective so I'm wondering if one of my assumptions is wrong. Maybe the product contains 2500 IU per ml? But that would make the % too high. Or, maybe it's per application? That might be about right. Unfortunately, I can't find anything on their website that specifies this.

Maybe I'm missing something. Does anyone else have thoughts on this?

That does makes sense. I just don't know the dosage: is it 2500 IU per gram? per application? per container?

Your assumption of per gram seems to the make the most sense but 0.075% is still very low for retinol. Typical use levels should be somewhere around 0.5% to 2% depending on the delivery system.

Again, I may be missing something here so if anyone else has a thought please let us know.

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