Enter a value and select the current standard to see equivalents in GSM, Bond, Text, Cover, Index, and Tag.
Enter the number found on your paper packaging.
Please enter a valid positive number.
GSM (Grams per Square Meter)
Bond / Writing (17″ x 22″) – lbs
Text / Book (25″ x 38″) – lbs
Cover (20″ x 26″) – lbs
Index (25.5″ x 30.5″) – lbs
Tag (24″ x 36″) – lbs
Select the standard associated with the input value.
Standard International Equivalent
0 GSM
Formula: Input × Factor = GSM
Equivalent Basis Weights (lbs)
Bond / Writing–
Text / Book–
Cover (Cardstock)–
Index–
Tag–
Visual Weight Comparison
Comparison of the input paper weight against common industry references.
Common Paper Weight Equivalents Table
Reference guide for standard commercial printing weights.
What is a Paper Basis Weight Conversion Calculator?
A paper basis weight conversion calculator is an essential tool for printers, graphic designers, and procurement specialists. In the paper industry, "weight" does not always refer to the physical heaviness of a single sheet in isolation, but rather to the weight of a standardized ream (500 sheets) of paper cut to a specific "basis size."
The confusion arises because different types of paper (Bond, Text, Cover, Index, Tag) have different basis sizes. For example, a 50lb Bond paper is actually heavier and thicker than a 50lb Text paper. This calculator unifies these disparate standards by converting any input value into GSM (Grams per Square Meter), which is the universal, non-variable standard for paper density.
You should use this tool if you are comparing quotes from different paper mills, switching from US standards (lbs) to International standards (GSM), or trying to match a specific paper thickness for a print project.
Paper Weight Formulas and Mathematical Explanation
The conversion between North American basis weights (lbs) and the International standard (GSM) relies on fixed conversion factors derived from the physical dimensions of the basis sheet.
The core formula to convert any Basis Weight (lbs) to GSM is:
To convert from GSM back to lbs, the math is reversed:
lbs = GSM / Conversion Factor
Practical Examples (Real-World Use Cases)
Example 1: Office Copy Paper
Most standard office copy paper in the US is labeled as "20lb Bond". A user wants to know the GSM equivalent to purchase compatible paper from a European supplier.
Input: 20 lbs
Type: Bond
Calculation: 20 × 3.759 = 75.18
Result: ~75 GSM (often rounded to 75gsm or 80gsm in commerce).
Example 2: Business Card Stock
A designer specifies "300 GSM" paper for business cards, but the local US printer uses "Cover" stock in lbs. What stock should be requested?
Input: 300
Type: GSM
Target: Cover (lbs)
Calculation: 300 / 2.704 = 110.9
Result: ~111 lbs. The printer would recommend "110lb Cover" stock.
How to Use This Paper Basis Weight Conversion Calculator
Identify Your Source Value: Look at the packaging of your current paper. Find the number associated with "lb", "#", or "gsm".
Select the Unit: In the "Current Unit Standard" dropdown, select the type of paper. Note: If the package says "Bond" or "Writing", select Bond. If it says "Offset" or "Book", select Text.
Enter the Weight: Type the numeric value into the "Weight Value" field.
Read the Results:
The large highlighted number shows the GSM equivalent.
The list below shows how this weight translates to other paper types (e.g., how a Text paper compares to Cover stock).
Use the Chart: Visual bars help you compare your input against standard industry benchmarks like "Newspaper" (Light) or "Business Card" (Heavy).
Key Factors That Affect Paper Basis Weight Results
While this calculator provides mathematical equivalents, several physical factors influence the actual feel and performance of the paper:
Caliper (Thickness): Weight does not always equal thickness. A "high bulk" paper may weigh the same as a standard sheet (same GSM) but feel thicker due to air pockets in the fiber.
Coating: Coated papers (Gloss, Matte) are denser. A 100lb Gloss Text will feel thinner than a 100lb Uncoated Text, even though they weigh the same, because the clay coating adds mass without adding much volume.
Moisture Content: Paper is hygroscopic. High humidity can slightly alter the actual weight of physical stock, though nominal basis weights remain constant for purchasing.
Fiber Content: Papers made from 100% cotton rag (often used for letterheads) have a distinct density and stiffness compared to wood pulp papers of the same calculated weight.
Grain Direction: While grain doesn't change the weight calculation, it affects stiffness. A lighter weight paper can feel stiffer if cut "grain long" versus "grain short."
Milling Tolerances: Paper manufacturing has a tolerance of usually ±5%. A calculated 100 GSM sheet might physically weigh between 95 and 105 GSM in a lab test.
Frequently Asked Questions (FAQ)
1. Why is 80lb Text lighter than 80lb Cover?
They have the same "lbs" number but different basis sizes. 80lb Text is weighed based on 500 large sheets (25″x38″), while 80lb Cover is weighed based on 500 much smaller sheets (20″x26″). In reality, 80lb Cover is more than twice as heavy as 80lb Text.
2. What is the difference between GSM and Basis Weight?
GSM (Grams per Square Meter) is fixed area measurement and is constant regardless of sheet size. Basis Weight (lbs) depends on the arbitrary "Basis Size" of the paper grade.
3. Is 20lb Bond the same as 50lb Text?
Yes, they are virtually identical. 20lb Bond ≈ 75 GSM, and 50lb Text ≈ 74 GSM. They are often used interchangeably in copiers and offset printing.
4. What is the standard weight for a business card?
Standard business cards are usually printed on 14pt or 16pt stock, which roughly converts to 100lb-130lb Cover or 270-350 GSM.
5. Can I use this calculator for cardboard?
Cardboard is often measured in "Points" (caliper) or Flute rating rather than basis weight. However, solid bleached sulphate (SBS) boards often use GSM or Cover weight, which this tool can calculate.
6. Does coating affect the conversion?
Mathematically, no. 100lb Gloss Text and 100lb Uncoated Text both convert to roughly 148 GSM. However, they will feel different in thickness.
7. What is "M-Weight"?
M-Weight is the weight of 1,000 cut sheets of a specific size. It is used for pricing and shipping, whereas Basis Weight describes the paper density.
8. Is higher GSM always better?
Not necessarily. Higher GSM means thicker, heavier paper, which implies quality for business cards but might be too stiff for brochures that need to fold flat without cracking.