A Guide to Plastic bags
An explanation of the sizes
In the standard format for describing a bag:
The width of the bag is always taken to be the side that opens, so this is normally, but not necessarily, the shorter side.
The width of the bag is given before the length.
The thickness of the bag is given last and is usually expressed in 'gauge' (100 gauge = 1/1000 of an inch).
The size of a bag is given as: Width (inches) x Length (inches) x Thickness (Gauge)
For example: if a bag is said to be 4" x 6" x 150 gauge then the bag is 4" wide by 6" long with 150 gauge thickness and the bag will open on the 4" width.
How thick is thick?
100 gauge a 1/1000 of an inch
120 gauge 'light duty' - good for protective covering
250 gauge 'medium duty' - good for holding light materials
500 gauge 'heavy duty' - where strength is required
Metric and Imperial
Most measurements are given in imperial (inches and gauge) but some of us prefer to use metric scales and the conversions are as follows:
width/Length 1" = 25.4 mm
400 gauge = 100 micron
For example: a 4"x 6" x 150 gauge bag is the same as a 102mm x 152mm x 37.5 micron bag
Some bags have a gusset at the sides to help the bag open out more and enable a greater volume of items to be put in - a good example is a refuse sack. Others have a gusset at the bottom to enable a wide product to fit in - a good example is a carrier bag.
A side gusset is expressed as a bag being x" wide opening to y" wide. For example: if a refuse sack is 16 x 25" x 39" this means it is 16" wide opening to 25" wide when the gusset is opened, with a bag length of 39".
A bottom gusset is expressed as + x". For example: if a carrier bag is 15" x 18" + 3" then the carrier is 15" wide by 18" long with a bottom gusset of 3"