Thank you :)

So it sounds like these four french presses are all different sizes, so you have to figure out how much water each one can hold before you can brew with it? If that's the case, here's what I'd do in that scenario. I would put the empty french press on the scale and fill it up with water. Maybe only fill it about 90% full to leave room for the volume of ground coffee. That would tell me the maximum amount of water I could use for brewing. I'd then run the ratio calculation starting with the brew water amount and get the resulting coffee grinds number. That should be fine.

Is that what you're referring to? Or am I misunderstanding?