Paper Measurements- GSM vs Microns

How does this affect us, what is best? More microns; ie a thicker board? Or more GSM; ie a heavier board? It is a balance that depends on the job on hand. We are experts at this and can be trusted to select the best product for the job. Simply put; a 300 gsm board with more microns is going to be thicker than a 400 gsm card that has less microns of bulk.

In South Africa, paper is measured in grams per square meter. When you read GSM on the paper specs it is how many grams a single square meter of paper weighs.

The most common sheet weights generally are: 80gsm90gsm100gsm120gsm130gsm150gsm and 170gsm.
Photo copiers and other lower quality needs often use 80gsm; letterheads should be printed on weights from 100gsm to 120gsm. 130gsm or 150gsm are great for leaflets or flyers as there is little or no show though with double sided print.

“Boards” would be sheet weights in excess of 170gsm. When you read specs on boards, you will see a measurement of thickness in microns. 1 micron = 1/1000 of a millimeter. Different sheets may weigh the same in GSM but have different values in microns.

To illustrate with timber planks, a plank of pine and an identical plank of Teak would be the same thickness but in weight the Teak would be very much heavier than the Pine.

These differences in Microns with Boards we use in printing are a result of many factors in the manufacture process of the board or boards in question. Some of the factors that impact these specifications are; Coating of the board, the natural bulkiness of the raw material or the amount of virgin fibers used in that paper’s manufacture.

Paper (sub 170gsm) is not that extreme in variations, hence the absence of the micron measurement. Still, print jobs using different stocks may carry subtle variations. Many uncoated boards with cheaper grades will carry the same thickness but weigh less than a superior a-grades substrate.

The  most Common board weights and their approximate thicknesses are as follows:

  • 200gsm =  150 to 220mics
  • 250gsm =  190 to 285mics
  • 300gsm =  237 to 342mics
  • 350gsm =  284 to 395mics
  • 400gsm =  315 to 460mics

Business cards are commonly 300gsm to 400gsm, and postcards can be found printed on 250gsm to 350gsm.

Paper and boards are sold in GSM, microns are not referred to that often.

I have been in the printing business for 15 years. I have dealt with many many different boards. I select our papers and boards with extreme care for the end product. With my experience and genuine desire to produce a quality and durable product range please be sure I am not selling you short by sticking to my choice in print substrates.


Lithographic Print Manager , Sure Print