I used to have a bean to cup machine and this is basically the only way I could do it with a single hopper. I didn’t weigh it. I just used a scoop and got it down so I could eyeball the amount of beans per serving. It’s not too onerous. The thing to keep in mind is that most of these machines use a timer to dose the beans, so it’s not by weight. It also varies by beans, roast etc. Some beans will take longer to grinder than others. Finally I’d always aim to put slightly less beans in the hopper than the machines timer called for, to make sure there wouldn’t be any left for the next cup.