A listing states 666 g or 2 kg. It does not state portions, and portions are what a kitchen is buying.
Four variables set the figure, and a single quoted number is a guess. The preparation: a firm whipped cream draws on gas differently from an aerated foam or an infusion. The dispensing equipment and its settings. Whether each charge is run out completely. And how often the system is opened, since every reset carries a cost.
The workable approach is to measure your own throughput. Log how long one unit lasts across a normal week, then set the listed sizes against that number. A week from a 666 g unit is comfortable. Two days from one means the cost is landing as interruption, and 2 kg or 4.33 kg resolves it.
The same logic makes the honest case for the 5 kg and 10 kg tanks. Not capacity as an end, but a service line that does not pause for a unit change.
Verify the size you select against the current manufacturer instructions for your regulator or siphon. Products are supplied for lawful culinary and food-service use within the applicable regulations.
