Proper Inner Bag Sizing For Bag in Box Packaging

John Panaseny
Tue, Aug 30, 2016


In order for efficient packaging and loading of bags into cartons for bag in box packaging, it is very important to size the bag for the carton to prevent loading jams and product damage.

The two main bag dimensions to consider for this are the bag girth and length.

Determining appropriate bag girth

Bag girth = [(carton width + length) x 2] – ½” (12 mm)


To measure bag girth:

  • Flatten a carton so that length and width now make one dimension
  • Place an empty bag over the carton with one edge of the bag aligned with one edge of the carton
  • Flatten the bag across the flattened carton
  • The proper flattened bag girth should be ¼” +/- 1/16” (6 mm +/- 1.5 mm) less than the flattened carton (carton length + width)

If the bag does not measure up properly then the vertical seal dimension and the forming set size should be checked.

Determining appropriate bag length

Bag length = carton width + carton depth – ¼” (6 mm) See above carton drawing for dimensions

To measure bag length:

  • Place a closed and glued carton on a tabletop or flat surface (do not flatten as stated above)
  • Lay an empty bag on the face panel of the carton with the bag folded over the edge of the carton and just touching the tabletop or flat surface.
  • The other end of the bag should be ¼” away from the other end of the face panel top edge which equates to the carton width plus depth dimension.
  • For example, if the carton width plus depth dimension is 10”, then the bag length should be 9 ¾”
    If this is not the case then the feed on the VFFS needs to be adjusted accordingly.

Once the bag is properly sized, then the next most important factor to check is the amount of air in the bag.

Determining appropriate bag deflation

To measure the proper air in the bag:

  • Place a filled bag into the cartoner bucket
  • Lay your spread out hand onto the bag
  • Determine how far you can press your spread hand into the bag
  • The appropriate amount of air in the bag should only allow you to just barely touch the product when pressing down
  • Too much air will not allow you to touch the product and too little air will allow you to fully touch the product
  • Too much air will make for loading issues and too little will help prevent proper settling of the product in the bag

Download the VFFS Machine Comparison Chart