GSM stands for grams per square metre and PT stands for point. Both units are used in measuring the thickness of packaging material, typically paper and cardboard. However, we typically get some kind of variation of this question from our customers: “What’s the difference between the two systems?”
To answer this question, we’ve provided some more insight on these measurements.
Grams per Square Metre – GSM
GSM is the metric equivalent of a point, but it relies on centimetres (cm) and metres (m), instead of inches (in). Typically, printers will refer to this unit system when buyers are looking at different paper levels.
As a rule of thumb, the higher the GSM, the thicker the stock will be. Simple, really. Also, papers with higher GSMs usually represent higher quality because they’re more durable since they’re thicker.
Nevertheless, it’s important to understand that more thickness doesn’t simply translate into more weight. It actually depends on the material you’re measuring. Moreover, the higher quality paper may not be suitable for your specific needs. Always consider the quantity and quality you need, and its impact on shipping or mailing costs.
The process of decision-making can be easier if you know the exact GSM, or at least a range, that you want.
Here are some general GSM weights and their uses:
- 35 to 55: Newspapers – Paper with this weight is extremely thin and delicate to touch.
- 90 to 100: “Printer Paper” – Paper at this weight is similar to the paper we use in our home or office printers.
- 120 to 140: Posters & Bulletins – Paper at this weight is a bit more stiff than the everyday, common-use paper.
- 210 to 300: Booklets & magazine Covers – This weight of paper is more resistant to being bent.
- 350 to 400: Greeting & Business Cards – This is the level of thickness that many people refer to as card or cover stock. These include the many paper thicknesses that are used in the packaging industry and to print business cards and wedding invitations.
Point System – PT
PT is another measurement that can calculate the thickness of paper by using the caliper of that paper. Paper printers and manufacturers will measure the caliper of the paper using a micrometer (one millionth of a metre).
Essentially, a point is equal to 0.001 inches or one thousandth of an inch. 10pts would represent a stock thickness of 0.01 inches.
That being said, the point system is used between our production team and suppliers when calculating the weight of paper for shipment. It’s also used to determine which machine the selected stock will be printed on.
Similar to the grams per square metre system, the higher the point, the thicker stock will be, and therefore more durable as well.
GSM to Point
Although the GSM system is a metric equivalent to the PT system and both calculate thickness, there’s one major difference. Grams per square metre will consider the weight of the stock in its calculation, whereas the point system won’t.
However, since a lot of packaging materials are standard, we’ve provided the following conversion chart to help your understanding.
For the purpose of packaging and creation of business cards, stocks that are greater than 14 points are used. It’s also important to note that more thickness doesn’t always mean more weight.
The Impact on Packaging
Points or grams per square metre alone cannot be the deciding factor when choosing packaging material. These are only measures of thickness and weight but other units of volume and density also play a role in selecting the correct packaging for you.
In case you’re overwhelmed, read our blog post on packaging unit conversions as a reference guide.
The actual material and its properties need to be considered top priority. Some materials have smoother surfaces, which makes the printing job easier, while others are coarser. The quality of the print can also be impacted with the selection of specific materials.
The right packaging material will provide protection for your products, a unique printing surface for your design, and a special feel for your clients.
Our in-house production coordinator can help with conversions and our custom packaging specialists will take care of the rest! We even have an inventory of samples you can see and feel before making the final decision!
Contact us today for a free consultation!