What is GSM? A Guide to Paper Weight and Usage

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GSM stands for grams per square metre, a measurement used to determine paper thickness and weight. Simply put, the higher the GSM number, the heavier and thicker the paper. This measurement is often called the paper’s grammage. For instance, a 150 GSM flyer feels thin and can easily be folded, whereas a 250 GSM flyer feels considerably thicker and sturdier.

What is GSM?

GSM stands for grams per square metre, a measurement used to indicate the weight and thickness of paper. The higher the GSM number, the heavier, thicker, and sturdier the paper. GSM helps you choose the right paper type for printing, packaging, or designing promotional materials.

Selecting the correct GSM is crucial to avoid costly mistakes, whether printing, packaging, or designing promotional materials.

In this article, we’ll explain the importance of GSM, outline the different types available, and guide you in choosing the best GSM for your needs.

Common GSM Paper Types and Their Uses

Knowing the various GSM ranges helps you select the ideal paper for printing, drawing, or promotional projects. Here’s a breakdown of the most common GSM categories:

GSM Range	Common Uses	Standard References
35-55	Newspapers, tracing paper	ISO 536, DIN 19309
75-90	Sketch pads, notebooks, stationery	ISO 216, ISO 536
90-100	Standard printing paper, basic documents	ISO 216, ISO 9706
120-140	Posters, brochures, flyers	ISO 216, ISO 536
210-300	Magazine covers, promotional flyers, art paper	ISO 216, ISO 9706
350-450	Cardstock, business cards, invitations, packaging	ISO 216, ISO 9706

35-55 GSM: Light and Delicate

The lightest papers range between 35 and 55 GSM. They are thin, flexible, and nearly transparent. Common uses include tracing paper and newspapers.

Architects and artists often use tracing paper for transferring designs and sketches due to its transparency. Newspapers prefer this GSM because it’s affordable, easy to fold, and suitable for mass distribution, although it’s less durable.

75-90 GSM: Sketch Pads and Notebooks

Paper between 75 and 90 GSM is commonly found in sketch pads, notebooks, and stationery. It’s suitable for pencil sketches and everyday note-taking, making it popular with students, artists, and office workers.

However, it’s relatively thin, heavier inks, markers, or paints might cause bleed-through or warping.

90-100 GSM: Standard Printer Paper

Most household printer paper falls within 90 to 100 GSM. This is ideal for standard printing tasks such as letters, documents, and assignments.

A higher GSM paper is recommended for documents that require a more premium look and feel, such as résumés or certificates.

120-140 GSM: Posters and Promotional Material

Posters commonly use paper weighing between 120 and 140 GSM, which provides durability. This range is robust enough to be displayed without easily tearing yet light enough to roll up for convenient transport.

This GSM is also popular for brochures and flyers, offering a professional appearance without the higher costs associated with thicker premium papers.

210-300 GSM: Magazine Covers and Watercolor Paper

Papers within the 210-300 GSM range are noticeably thicker and sturdier and are used for magazine covers and higher-quality promotional flyers, providing durability while remaining flexible enough for frequent handling.

Watercolour paper also typically falls into this category due to its ability to absorb water without warping.

Artists prefer 210-300 GSM because it is strong and absorbent under various painting techniques.

350-450 GSM: Cardstock and Invitations

The heaviest papers, ranging from 350 to 450 GSM, are categorised as cardstock. These papers are thick and sturdy, resembling thin cardboard. Cardstock is often used for business cards, invitations, and greeting cards, giving them a premium, professional feel.

Due to its stiffness and durability, cardstock is excellent for printed items that need frequent handling or must leave a strong impression, such as wedding invitations or luxury packaging.

GSM vs Other Paper Weight Measurements

While GSM is a universal measurement of paper weight used worldwide, you might encounter other terms, especially in North America, such as Bond, Cover, Index, Tag, and Offset. These categories are based on traditional paper usage rather than actual physical weight. Each type has its unique basis weight measured in pounds (lbs), making comparisons challenging.

Quick Example

Type of Paper (US)	Basis Weight (lbs)	Equivalent GSM
Bond Paper	20 lbs	~75 GSM
Cover Paper	80 lbs	~216 GSM
Index Paper	110 lbs	~199 GSM
Tag Paper	100 lbs	~163 GSM

To simplify things:

GSM measures paper weight universally as grams per square metre.
Bond, Cover, Index, and Tag refer to North American standards defined by their respective basis weights in pounds.
Points or Caliper measure the physical thickness of paper in thousandths of an inch or millimetres, focusing purely on thickness rather than weight.

For international simplicity, GSM remains the easiest and most reliable standard.

While this guide helps clarify the importance of GSM, it’s equally essential to select high-quality equipment and packaging solutions to ensure your products and materials stand out.

At Triton Store, we specialise in thermal labels, thermal printers, packaging material, and machinery for the food packaging industry. Visit our website today to discover reliable solutions designed to enhance your business.