Paper Thickness and Weight Explained
Are you feeling confused and overwhelmed by all the technical terminology relating to paper thickness and weight? Well, take courage, because you’re not alone – even those of us with many years of print industry experience are still learning new things every day, and when it comes to paper (or ‘stock’ to use the proper term), there’s certainly a lot to know!
What does ‘GSM’ mean?
The term ‘GSM’ simply stands for ‘Grams per Square Metre’ and is used for measuring paper weight. Put simply, if you were to take a 1m² piece of a certain type of paper, how much would it weigh in grams?
As a unit of measure, GSM connects the wood pulp producers (who sell by weight) with the paper mills (who work on area). Generally, the higher the GSM the more wood pulp is required to produce the paper – for example, one square metre of 400gsm board will use a lot more wood pulp than a square metre of 100gsm paper.
However, be aware that GSM is a measure of paper weight and doesn’t necessarily directly relate to paper thickness. More on that shortly…
What does ‘Mic’ mean?
‘Mic’ is an abbreviation for ‘Microns’, a unit of measure used for gauging paper thickness. One micron = 1000th of a millimetre, hence 250mic = 0.25mm and 1000mic = 1mm.
This is where things can get confusing because GSM and Microns are not necessarily directly proportionate to each other. For example, one brand of 100gsm paper can be thicker (in Microns) than another paper of the same weight (in GSM) due to the type of wood pulp it’s made from or ‘bulking’ methods used in its construction. Other manufacturing processes such as ‘calendering’, involve paper being passed between high pressure rollers which compress the fibres, resulting in paper that is thinner and denser but not affecting its weight per 1m².
To help you make sense of all this, we’ve listed some common paper weights and their corresponding thicknesses in the quick-reference tables below.
(Please be aware that this information should only be used as a guide because relative gsm/mic can vary from one brand of paper to another and there can even be some minor variation in different production batches of the same type of paper).
|Uncoated Paper (also referred to as Bond, Offset or Laser)|
|70gsm||90mic||Thin document paper|
|80gsm||100mic||Standard copy paper|
|90gsm||112mic||Standard copy paper|
|100gsm||125mic||Standard Letterhead paper|
|120gsm||150mic||Premium Letterhead paper|
|350gsm||400mic||Thick postcard board|
|400gsm||480mic||Thick business card board|
|Coated Paper (Gloss, Silk, Matt)|
|70gsm||60mic||Very thin magazine paper|
|80gsm||70mic||Very thin magazine paper|
|90gsm||78mic||Thin catalogue paper|
|100gsm||87mic||Thin catalogue paper|
|115gsm||98mic||Thin brochure paper|
|130gsm||110mic||Standard leaflet paper|
|150gsm||128mic||Standard leaflet paper|
|170gsm||145mic||Premium leaflet/brochure paper|
|200gsm||175mic||Heavyweight leaflet paper|
|400gsm||380mic||Thick business card board|
As you can see, we’ve focused on metric units of measure but there are imperial equivalents. American paper weights are calculated in pounds (lbs) based on different types or categories of paper (Bond, Text, Book, Cover, Index and Tag). Paper thickness can also be measured in ‘thou’ (1/1000 of an inch) and with 4 inches being equal to 101.6mm a simple way to convert either way is to work on approximately 4 thou per 100 microns.
Hopefully that’s helped to unravel some paper-related mysteries for you? Should you have any further questions, or would like to discuss an upcoming print project, don’t hesitate to call us on 01444 236204 or drop us a line – we’d love to chat!