500 g =0.5 kg

1

500g per bag. 12 generation per box, box gauge:

12000 (0.5×12) = 2000 cases.

2

250 grams per bag. 18 with box, box gauge:

12000 ÷ (0.25× 18) = 2666.66.

Option 1 is suitable, at least 2000 cases.