Is it for a Syrian or a dwarf hamster? I don't use an actual sand bath for a syrian, just a corner litter tray with sand in - neither of our syrians have been bothered about sand baths. For dwarf hamsters, most people feel they need and enjoy a sand bath/dish of sand and may also use it as a toilet as well.
For a toilet litter tray, I use these
Not too big, not too small and it's open at the top so they can get in and out easily. Big enough to pee in the very back corner (so neat of them!) and sit in the front for a wash. It also fits in the corner of a cage. Syrians tend to choose a corner of the cage for a toilet - so wait and see where the hamster chooses, spot clean the pee and add a bit more substrate to replace, and put the litter tray there, with the sand in and a tiny bit of pee'd on substrate on top the first time so they know it's still their pee corner. If you put it anywhere else they will ignore it
https://www.amazon.co.uk/Trixie-Corn...gateway&sr=8-7
I am also not good at converting kg to litres lol. But for comparison the 10kg bag of Fitch would probably easily fill three 100cm cages to about 6" deep. Whereas the biggest bag of Kaytee I doubt would fill a single 100cm cage to 6" deep.