Answers. 1  Because of it's density it does not measure the same as what one normally thinks when measuring a plain liquid such as water. If you take one cup of water and one cup of sweetened condensed milk and set them on scales side by side you will find that the sweetened condensed milk weighs more than the cup of water. So it is one of those things that is best to measure properly. A 14 oz can of sweetened condensed milk is just a little more than a cup.