basically, because you measure your weights in a bowl, and a bowl is not very useful for pouring liquids. also, if you want to use your bowl to measure the liquid first (say, for a bread dough), you'd end up with having to dry it very thoroughly before adding the flour to it (if you don't, you'll have flour sticking to the bowl). as you will notice, i've very ingeniously NOT used the word for that thingy you use for measuring liquids. you know, this transparent plastic thingy with a scale on its side that is most useful: you hold it under the tap and just pour water into it what's it called, anyway? (bear with me, please, i'm danish.) oh boy, i hope this made sense. Thanks for trying to answer my question, oraklet. I measure my weights in whatever's handy, actually. I place my ingredients in all kinds of vessels - Cup, measuring cup, bowl, plate, etc and then add them at the appropriate time to my recipe, after I've weighed them. Every container in my kithen under 3kilos in weight has been used to hold things on my scale at one time or another. It's easy to weigh a liquid in any vessel, really. Oh well. It will remain one of the great big mysteries of the world to me. ← I think the answer is that dry ingredients are weighed and liquid ingredients are measured by volume. Therefore you can never get rid of your measuring cup which probably has a dual scale for US and metric measuring.