International paper weight conversion

International paper weights

How on earth can a piece of paper weigh 220kg?! Well, it can't, but a stack of 1000 press sheets can. The way paper weights are expressed in Japan can be a little confusing, particularly as many designers working overseas will likely be used to gsm (grams per square meter), or lbs in the US, rather than kg weights.

Japanese papers are classified according to the weight of a stack of 1000 sheets of bench mark sized sheets. There are many different paper sizes in use by commercial printers in Japan, each affecting the weight of a stack - but we use the standard shirokuban (四六判) paper size (788 x 1091mm) as the bench mark. The weights commonly used in Japan are 55kg, 70kg, 90kg, 110kg, 135kg, 180kg, 220kg, and 260kg.

GSM to KG conversion

The gsm to kg calculation is simply gsm weight x 0.86 = kg weight (using shirokuban size sheets).

LB to GSM conversion

The calculation for lbs to kg is complicated by the fact that US paper weights are further classified into three types of paper - text (internal pages / thin paper), cover (cover pages / thick paper), and bond (general use/ office paper). We first need to convert the lb weight into the GSM weight before we can further convert to the kg weight. For text stock we use the formula lbs x 1.48 = gsm weight. For cover stock we use lbs x 2.707 = gsm weight.

We have provided the table opposite as a guide to working it all out but we recommend getting your hands on our paper sample books to really get a feel for the weights.