FORMULAS FOR WEIGHT OF POLY BAGS

When sourcing poly bags, it is critical to know the weight per M bags, so you can determine how many total pounds of poly your are sourcing.  Very few mills will run less than 500# per size (although there are some specialty small-run companies who specialize in this, at higher cost per pound).  Film manufacturers who run 500# to 1000# cost-effectively may not be the best choice for runs of 2000#, 5000# or 10,000.  Conversely, long-run hi-speed manufacturers will often not want to run les than 2000# (or certainly not less than 1000#).

The variables in the calculation are:           Width, Gusset (if any), Length, Gauge, and Resin Type (constant of 15 or 14.5).

LDPE or LLPDE – Flat:                   (W x L x GA)/15 = Wt per M bags

                        Ex:  10x12 .002            (10x12x2)/15 = 240/15 = 16# per M bags

           

LDPE or LLDPE – Gusseted:        ((W+G) x L x GA)/15 = Wt per M bags

                        Ex: 12x3x18 .002         ((12+3)x18x2)/15  =  540/15 = 36# per M bags

                        Ex:   8x2x12 .002      ((8+2)x12x2)/15    =  240/15 = 16# per M bags

HDPE – Flat:                                                (W x L x GA)/14.5  = Wt per M bags

            Ex:  24x24” 12-micron  =  (24x24x0.472)/14.5  = 271.872/14.5  = 18.75# per M bags

HPDE – Gusseted:                         ((W+G) x L x GA)/14.5 = Wt per M bags

            Ex: 12x3x18 10-micron = (15x18x.0.402)/14.5  = 108.54/14.5  =  7.49# per M bags

To get weight per roll (or per case), you need to know number of bags per roll (or per case), and simply multiply by the pack (as a fraction of 1000).