How to calculate the weight of paper?
The weight of paper, also known as grammage, is a key indicator to measure the quality of paper. It is denoted in grams (g), and represents the weight of a square meter (1m²) of paper.
The formula for calculating it is: Grammage of paper (g/m²) = Weight of paper (g) / Area of paper (m²).
For instance, if you have an A4 sheet of paper, its standard dimensions are typically 210mm x 297mm, which gives an area of about 0.06237 square meters. If this A4 sheet weighs 5g, then the grammage is calculated as: 5 g / 0.06237m² = 80.19 g/m². This means that every square meter of this sheet weighs 80.19 grams.
So, if you know the size and weight of the paper, you can calculate its grammage.
The Commonly Used Printing Papers in Publishing
Copperplate Paper
Also known as coated printing paper or powder paper in some areas like Hong Kong. It’s a premium printing paper made by coating base paper with white coating. Primarily used for high-end book covers, illustrations, color pictures, and various exquisite advertisements.
Common Types: Single-side copperplate, double-side copperplate, matte copperplate, and embossed copperplate. Classified by quality as A, B, C.
Common Weights: 70, 80, 105, 128, 157, 180, 200, 230, 250, 300, 400, 450 gsm.
Pros: Vivid colors, great ink absorption, high color reproduction, suitable for photos, landscapes, and colorful postcards. Can be laminated for enhanced texture. Smooth texture adds sophistication.
Cons: Not suitable for pens or gel pens due to smoothness, ink smudges easily. Relatively moderate hardness compared to papers of the same weight. Affordable but prone to curling and moisture damage.
Matte Coated Paper
Characteristics: Also known as matte coated paper or non-glossy copperplate paper. Less reflective under sunlight compared to copperplate paper. Usually thinner and whiter than copperplate, more ink-absorbent, and harder, less prone to deformation.
Common Uses: High-end product catalogs, showcasing elegant and simple products like instruments, calligraphy, and antiques, or magazines featuring photos or illustrations, emphasizing a matte finish.
Common Weights: 105, 128, 157, 200, 250, 300 gsm.
Pros: Easy to color. Comparable to card paper in front surface feel. Cost-effective.
Cons: Relatively soft. Similar hardness to 250g card paper for 300g matte coated paper. May not be suitable for postcards. Lacks the thickness of card paper and the vibrant colors of copperplate paper.
White Cardboard
Characteristics: Made entirely from bleached chemical pulp and fully bonded single or multi-layered paper, typically with a weight above 150 gsm. Known for its high smoothness, good stiffness, neat appearance, and uniformity.
Common Uses: Business cards, certificates, invitations, covers, monthly calendars, postal postcards, etc.
Common Weights: 200, 250, 300, 350, 400 gsm.
Pros: Thick and stiff. High hardness among papers of the same weight. Great color rendition, not inferior to copperplate paper. Backside writing can be easily erased. Mid-range price, ideal for postcard paper selection.
Cons: Prone to scratching, easily marred from printing to writing and daily handling. Often laminated for scratch resistance. Dark colors leave marks with minimal contact. Vulnerable to curling, especially in windy conditions.
Dowling Paper
Characteristics: “Dowling Paper”, officially known as offset printing paper or offset paper, is a premium book and magazine printing paper. It demands high requirements for contrast, stretch ratio, and surface strength during printing, and its acidity or alkalinity should be close to neutral or weakly alkaline.
Common Uses: Suitable for monochrome or multicolor book covers, text, inserts, posters, maps, promotional paintings, color trademarks, and various packaging.
Common Weights: 70, 80, 100, 120 gsm.
Pros: Minimal stretching, even ink absorption, good smoothness, dense texture, high whiteness, strong water resistance.
Pearlescent Paper
Characteristics: Consists of base fibers, fillers, and surface coatings. Smooth surface, thicker, strong reflection, pearl-like luster.
Common Weights: 120, 250, 280 gsm.
Common Uses: High-end albums, books, exquisite packaging, gift boxes, greeting cards, hangtags, etc.
Pros: Lightweight, good water resistance, tear-resistant, corrosion-resistant, foldable, sun-resistant, color does not fade, unique texture, strong three-dimensional effect, bright printing.
Cons: Average color printing effect (although often used for black-and-white drawings), somewhat difficult to glue, but sturdy after bonding.
Newsprint
Also known as white newspaper paper, it’s the primary paper for newspapers and books. Suitable for newspapers, periodicals, textbooks, comics, etc.
Characteristics: Light and soft, good elasticity, excellent ink absorption ensures ink stays well on the paper surface. Smooth on both sides after calendering, clear and full print on both sides, with a certain mechanical strength, good opacity, suitable for high-speed web printing.
Common Weights: National standards stipulate weights as 51g/m2, 48g/m2, and 46.5g/m2. However, there are different weights available.
Box Cardboard
Also known as hemp cardboard, it’s a sturdy cardboard used for various packaging, including books, groceries, radios, televisions, machinery parts, and food. Available in weights of 200 gsm, 310 gsm, 420 gsm, and 530 gsm. Smooth surface and good mechanical strength.
Embossed Paper
Embossed paper is the primary paper used for embossed printing of books and magazines. Suitable for important works, scientific books, academic journals, and college textbooks, among others.
Common Weights: 52 gsm and 60 gsm, available in both roll and flat papers. Slightly smoother than newsprint, longer storage life, but prone to dusting and shedding, unsuitable for offset printing.
Chipboard
also known as yellow cardboard or horse dung paper, is a yellow packaging paperboard. It is mainly used for packaging goods, making paper boxes, and as covers for account books. The weight ranges from 200 grams per square meter to 860 grams per square meter. Commonly used weights include 8号 (420 grams), 10号 (530 grams), and 12号 (640 grams). Chipboard requires tight and sturdy quality, smooth surface, and a certain level of mechanical strength and toughness.
Whiteboard
Whiteboard paper is a type of paperboard with a white front surface and a gray back surface, primarily used for single-color printing to make paper boxes for packaging or for design and handmade products.
Binding Paperboard
An essential material for bookbinding, including white cardboard, yellow cardboard, and box cardboard, mainly used to make hardcover book shells and covers. Hardcover book shells made of cardboard are sturdy, beautiful, and conducive to long-term preservation.
Calcium Sulfate Paper
Calcium sulfate paper is a high-quality packaging material made primarily from high-density polyethylene (HDPE), known for its aesthetics, non-toxicity, light weight, moisture resistance, high compressive strength, corrosion resistance, and good feel. It’s widely used in pesticides, machinery, chemicals, food, and other industries for inner and outer packaging, making it an ideal substitute for wood and paper packaging materials.
Kraft Paper
Kraft paper is a durable and water-resistant packaging paper, typically in brown-yellow color. It has a wide range of uses, commonly employed in making paper bags, envelopes, record sleeves, file folders, and sandpaper. The weight ranges from 40 grams per square meter to 120 grams per square meter, available in both roll and sheet form, with options for single-sided gloss, double-sided gloss, and striped patterns. Key quality requirements include flexibility, high tear resistance, ability to withstand significant tension and pressure without rupture.
Glassine Paper
Glassine paper is a thin film made from natural fibers such as cotton pulp and wood pulp, using adhesive methods. It is transparent, non-toxic, and odorless. Its impermeability to air, oil, bacteria, and water makes it suitable for food packaging purposes.
Also known as transparent paper, it is a high-grade packaging and decorative paper that is as transparent as glass. It is used for wrapping grains, food items, shirts, cigarettes, cosmetics, and other goods. The weight is typically 30 grams per square meter. In addition to clear colorless options, it comes in various colors such as golden yellow, peach red, and emerald green. Glassine paper is non-permeable, oil and water-resistant, flexible yet durable, colorless, transparent, and glossy. It can prevent moisture and rust when sealed but can easily tear if slightly damaged. Due to its high longitudinal strength, it can be used to make paper ropes. Waste glassine paper cannot be recycled.
Envelope Paper
Envelope paper is an extremely thin single-sided glossy writing paper, with a weight of only 20 grams per square meter. Originally used for stamp backing and sealing valuable letters, it is now primarily used in packaging cosmetics, fruits, and food items, as well as lining cigarette packages. After printing and waxing, it can be used as candy wrapping paper or substitute typewriter and carbon paper for printing invoices, receipts, or multi-page carbonless paper. Quality requirements include thinness, strength, good transparency, high tension, and low air permeability.
