@lanodan For every six units of carotene, one unit of retinol is produced, and that assumes you have enough bile salts in your gall bladder along with the digestive enzymes to convert it. You need to be in perfect condition (little to no stress, no digestion issues, not eating any processed foods, good amount of sleep, etc) to rely solely on plants for Vitamin A.

A medium sized carrot usually has around 500 micrograms of Vitamin A (carotene) which under perfect conditions would be converted to 83.3 micrograms of retinol. A glass of whole milk contains 112 micrograms of retinol. That may not seem that much more, but again, we are assuming perfect conditions.

https://www.quora.com/How-much-vitamin-A-is-in-a-100g-carrot (apologies for the Quora link)

https://www.weekand.com/healthy-living/article/much-vitamin-milk-18017900.php