I convert all the time and use 250ml per cup. For butter, I use 250gm per cup.

The booklet for my digital scale says 8.5 oz per US cup of milk, which is equivalent to 241 grams. In the US a cup is 240ml in the UK a cup is typically 250 ml, so essentially 1 ml weighs 1 gram. I hope this helps.

appreciate the info i have digital scales but no mesauring glasses or cup

Grams wouldn't apply to milk so 1 cup = 250 ml. But if you own a decent glass measuring cup odds are the conversons are already on there for you.

http://www.infoplease.com/pages/unitconversion.html?unittype=cooking