10IU (international units) of vitamin A = 6μg beta carotene =3μg retinol

One International Unit (I.U.) = 0.3 mcg. of retinol

= 0.6 mcg. of beta-carotene

= 1.2 mcg. of other total mixed carotenoids with vitamin A activity

http://www.fao.org/docrep/003/x6877e/X6877E22.htm

Both information varies only by unit but it is the same result. Thank you for sharing.

The 1:2 converison factor from betacarotene to vitamin A was used before the IOM proposed the new concept in 2001:

1 retinol activity equivalent (μg RAE)

= 1 μg of all-trans-retinol

=2 μg of supplemental all-trans-β-carotene carotene

= 12 μg of dietary all-trans-β-carotene

= 24 μg of other dietary provitamin A carotenoids