It should depend on whether you have a top loader or front loader. I have a FL which uses very little water, so I usually use 1/2 or 2/3 of a scoop -- it should be included in the smallest size bag, too, as that is what I buy. When I've had to wash dipes on vacation and only used top loaders, I always used one full scoop, even if washing on "small load" setting because even a small load setting had more than double the amount of water used by my FL at its maximum load. And Charlie's is very low on sudz; it says an entire scoop is supposed to dissolve in 1C water. Even then, I always do an extra rinse on my dipes, no mater what machine I use.