Guide to Paper Weight and Thickness for Optimal Printing

Have you ever been disappointed with subpar printing results? Often, the paper selection makes the crucial difference between mediocre and outstanding outcomes. From books and brochures to business cards and posters, different printed materials require specific paper weights and thicknesses. This comprehensive guide explores paper measurements and their impact on print quality, helping you select the perfect paper for any project.

Paper weight serves as a key indicator of density and quality, directly affecting thickness, strength, and rigidity. Two primary measurement systems exist:

Grammage, expressed as Grams per Square Meter (g/m²), represents the weight of one square meter of paper. This globally recognized standard allows direct comparison between papers worldwide. For example, 80 GSM paper weighs 80 grams per square meter regardless of sheet dimensions.

Common in the United States and Canada, basis weight measures paper in pounds (lbs). This system becomes complex because different paper types use varying "basis sizes" - the standard sheet dimensions used for measurement. For instance:

• 20 lb bond paper differs in thickness from 20 lb cover stock
• Text weight and book paper have different basis sizes

Approximate conversions between systems vary by paper type:

• Bond paper: 1 lb ≈ 1.48 GSM
• Cover stock: 1 lb ≈ 2.708 GSM

For example, 20 lb bond paper converts to about 30 GSM (20 × 1.48), while 60 lb cover stock equals approximately 162.5 GSM (60 × 2.708). These conversions serve as estimates, as actual values may vary slightly between manufacturers.

The International Organization for Standardization (ISO) established ISO 536, defining grammage as the official global measurement using g/m². This standardization facilitates international paper commerce and comparison.

Thickness refers to a sheet's vertical dimension, typically measured in microns (μm) or mils (0.001 inches). Thickness influences:

• Perceived quality and durability
• Stiffness and handling characteristics
• Opacity and show-through resistance
• Printing performance and ink absorption

Standard units include:

• Microns (μm): 1 μm = 0.001 mm (global standard)
• Mils: 1 mil = 0.001 inches (primarily US)

Conversion: 1 mil ≈ 25.4 μm

Several production elements determine paper thickness:

• Pulp composition: Long fibers create thicker sheets than short fibers
• Pressing: More intense pressing produces thinner paper
• Sizing: Additives that improve surface quality may reduce thickness
• Coating: Coated papers often appear thinner as coatings fill surface voids

These related properties further define paper characteristics:

• Bulk: Volume per unit weight (higher bulk = thicker feel at same weight)
• Density: Weight per unit volume (higher density = thinner feel at same weight)

For example, two 60 GSM sheets may differ in thickness - one with 1.5 bulk measures ~90 μm, while 2.0 bulk measures ~120 μm.

Thicker papers generally offer:

• Better ink absorption: Reduces bleed-through and produces richer colors
• Higher opacity: Minimizes show-through for improved readability

However, excessive thickness may cause feeding issues in some printers and increase production costs. Optimal thickness balances quality requirements with practical considerations.

Surface treatment creates two fundamental paper categories:

These feature mineral-based surface layers that enhance:

• Smoothness: Superior detail reproduction for sharp images
• Gloss: Ranges from high-gloss to matte finishes
• Color fidelity: Excellent reproduction with vibrant results
• Ink control: Moderate absorption prevents excessive dot gain

Common types include gloss coated, matte coated, and silk/satin finishes.

These retain natural fiber characteristics:

• Texture: Visible fiber patterns and tactile surfaces
• Absorption: Higher ink penetration creates softer colors
• Appearance: Subtle, organic aesthetic

Examples include bond, ledger, and text papers.

Choose based on project requirements:

• Coated: Vibrant marketing materials, photo books, brochures
• Uncoated: Business correspondence, literary books, stationery

Standard weight categories and typical uses:

• Bibles and reference books (reduced bulk)
• Aerogrammes and airmail (weight savings)

• Copy paper (80 GSM standard)
• Book pages (90-100 GSM)
• Business documents (90+ GSM)
• Resumes (105-120 GSM)

• Brochures and catalogs
• Magazine pages
• Photo books

• Book covers
• Premium brochures
• Business cards
• Invitations

• Packaging
• Premium business cards
• Hardcover book cases

Beyond standard varieties, specialty papers offer unique characteristics:

• Linen: Woven cloth-like appearance
• Laid: Subtle chain-line patterns
• Embossed: Custom raised designs

• Recycled: Post-consumer waste content
• FSC-certified: Responsibly sourced fibers

• Pearlescent: Iridescent finishes
• Metallic: Foil-like surfaces
• Synthetic: Waterproof polymer-based sheets

Tailor paper choices to specific applications:

Opt for 250-400 GSM card stock for durability and premium feel. Consider textured or specialty finishes for distinctive impressions.

• Brochures: 120-170 GSM coated for color fidelity
• Posters: 150-250 GSM for visibility
• Flyers: 80-120 GSM for cost efficiency

Select 250+ GSM card stock for structural integrity. Consider coatings or laminations for moisture resistance.

• Novels: 70-90 GSM for comfortable reading
• Art books: 120-170 GSM coated for reproduction quality

Understanding paper specifications empowers informed decisions for any printing project. By considering weight, thickness, coating, and specialty characteristics, you can consistently achieve optimal results that meet functional requirements and aesthetic goals.