Grammage of paper. The paper grades used in the liners and corrugating medium of corrugated boxes, are identified by it’s nominal weight, ie; mass of paper or board expressed in
grams/metre², or gsm.

Following are examples of the way that board grades are expressed, using the paper

112/112-112/1 B – this indicates a very lightweight board single wall grade in B flute

200/250-140/1 C – indicates a strong grade of single wall board in C flute

The first two numbers relate to the outside liner and inside liner, then the following number after the ’–‘ relates to the corrugating medium.

175/112/175-112/2 B/C – indicates a medium strength Twin Cushion (or Double Wall) board grade in B and C flute.

The first three numbers relate to the outside, centre and inside liners, then the following numbers after the ‘-‘ relate to the B flute and C flute corrugating mediums.

Following is a list of commonly used paper grades. The grammage may vary a little from supplier to supplier, but this guide will ignore those variations:

Corrugating medium:

112 gsm Recycled – often a dual purpose medium and liner

140 gsm Recycled or semi-chem

180 gsm Recycled or semi-chem

Liner paper:

112 gsm Recycled – often a dual purpose liner and medium

130 gsm Kraft liner

150 gsm Recycled or kraft liner

200 gsm Recycled or kraft liner

230 gsm Recycled

270 gsm Kraft liner

430 gsm Kraft liner

500 gsm Kraft liner

150 W/L or Env Recycled white liner

200 W/L Recycled white liner