Kg = (W + G) x L x T ÷ 532500 ÷ 1000 x B
where
 Kg = Weight of the order
 W = Width of the bag or tube (mm)
 G = Width of the gusset (if any) (mm)
 L = Length of the bag (mm)
 T = Thickness of bag wand (Microns)
 B = Number of bags

Kg = W x L x T ÷ 1065 x S
where
 Kg = Weight of the order
 W = Width of the sheet (m)
 L = Length of the sheet (m)
 T = Thickness of a single wand (Microns)
 S = Number of sheets

10000 bags of (400mm + 0) x 600mm x 100 mics
= 400 x 600 x 100 ÷ 532500 ÷ 1000 x 10000
= 450.7 Kg
Note the minimum thicknes for bags is between 22 to 25 microns (depending on the specific product size) 
50 sheets of 3 m x 30 m x 100 mics
= 3 x 30 x 100 ÷ 1065 x 50
= 422.5 Kg
Note that the width and length dimensions are kept in meters for the purpose of the formula
