Full Fat Half Fat Milk

[Iamcazzy]

I need to turn a certain volume of full fat milk into half fat milk. I don't want to go out and buy half-fat milk as I've got lots of full fat milk at home.
Can anyone tell me how much water I need to add to say 100ml of full fat milk to turn it into half fat milk please?
Sorry if I'm a bit of an airhead this afternoon but I can't get my head around this one!

TIA

[heathfield]

UK standardised whole milk has a fat conent of 3.5%.
Standardised semi-skimmed milk has a fat content of half that, i.e.1.7%.
So if you add 100ml - 3.7ml = 96.3ml water to whole milk, you'll get the same fat content as semi-skimmed.

[Iamcazzy]

Thank you heathfield. I suspected I should add somewhere near 100ml of water to 100ml of milk if half-fat milk was truly half fat, but I couldn't work out the exact amount of water.

I'm puzzled though about the 3.7ml figure. Where did you get it from?

Thanks

[heathfield]

Different breeds of cow produce milk with different fat content, Jersey cattle being one of the highest. The amount and type of feed can also affect fat content among cows of the same breed. To arrive at a standardised fat content, some of the cream is removed. There are several links on Google to the fat content of UK standardised milk, for example the Dairy Council website, here.