Instantly convert between GSM, Bond, Text, Cover, and Index weights
Enter the numerical weight value found on your paper packaging.
Please enter a valid positive number.
GSM (Grams per Square Meter)
Bond / Writing (lbs)
Text / Book / Offset (lbs)
Cover (lbs)
Index (lbs)
Tag (lbs)
Bristol (lbs)
Select the current unit or paper grade of your value.
Standard Metric Weight
0
GSM
Bond / Writing
–
Text / Book
–
Cover
–
Index
–
Formula Used: GSM = Bond Weight × 3.759. The paper weight conversion calculator derives the GSM metric standard from the specific basis weight and sheet dimensions of the selected grade.
Equivalent Weights Table
Paper Grade
Weight (lbs)
Basic Size (inches)
Weight Comparison Chart (GSM)
Comparison of your input against common paper standards.
What is a Paper Weight Conversion Calculator?
A paper weight conversion calculator is an essential tool for printers, designers, and publishers that translates the weight of paper between different industry standards. In the printing world, paper weight is not measured universally. While most of the world uses the metric standard of GSM (grams per square meter), North America utilizes a complex system known as "Basis Weight" measured in pounds (lbs).
The complexity arises because different types of paper (Bond, Text, Cover, Index) have different "Basic Sizes." Therefore, 20 lb Bond paper is not the same thickness or weight as 20 lb Cover paper. A paper weight conversion calculator bridges this gap, allowing you to instantly determine the equivalent weight of a sheet across all paper grades.
This tool is designed for print buyers who need to compare quotes, graphic designers specifying materials for a project, and anyone confused by why "heavier" paper sometimes has a lower pound rating due to its grade.
Paper Weight Conversion Calculator Formula and Math
To build an accurate paper weight conversion calculator, one must understand the relationship between the metric GSM standard and the Imperial Basis Weight system. The conversion relies on the "Basic Size" of the paper grade—the size of the sheet before it is cut down for commercial use.
The core formula to convert Basis Weight (lbs) to GSM is:
Practical Examples using the Paper Weight Conversion Calculator
Example 1: Office Copy Paper
Most standard office copy paper in the US is known as "20 lb Bond." If you are ordering printing from Europe or using a paper weight conversion calculator to find a metric equivalent, you would input "20" and select "Bond/Writing".
Input: 20 lbs (Bond)
Calculation: 20 × 3.76 = 75.2
Result: ~75 GSM
This explains why standard international copy paper is often 75gsm or 80gsm.
Example 2: Business Card Stock
You want a sturdy business card and see a specification for "300 GSM" cardstock. You are familiar with "Cover" weights. Using the paper weight conversion calculator:
Input: 300 GSM
Calculation: 300 ÷ 2.70 = 111.1
Result: ~110 lb Cover
This tells you that 300 GSM is roughly equivalent to 110 lb Cover stock, a very standard heavy weight for business cards.
How to Use This Paper Weight Conversion Calculator
Getting accurate results from this paper weight conversion calculator is simple if you follow these steps:
Identify Your Current Value: Look at the packaging of your paper ream. Find the number (e.g., 80, 100, 24).
Select the Correct Unit/Grade: This is critical. Is it "80 lb Text" or "80 lb Cover"? These are very different papers. If the number is followed by "gsm", select GSM.
Review the Primary Result: The calculator will immediately show the GSM equivalent, which is the best baseline for comparison.
Check Intermediate Values: Look at the grid to see what that same paper would weigh if it were classified as a different grade.
Use the Copy Button: Save your results to your clipboard for email quotes or project specs.
Key Factors That Affect Paper Weight Conversion Results
When using a paper weight conversion calculator, keep in mind that calculated weights are theoretical mathematical equivalents. Several physical factors affect the actual feel and thickness of the paper.
Caliper (Thickness): Two papers can have the same weight (GSM) but different thicknesses depending on how tightly the fibers are pressed. High-bulk papers feel thicker than their weight suggests.
Coating: Coated papers (gloss or matte) are denser. A 100 lb Gloss Text will feel thinner than a 100 lb Uncoated Text, even though they weigh the same on the scale.
Fiber Content: Papers made with cotton fibers (like resume paper) often have a different density compared to wood pulp papers, slightly affecting the accuracy of a standard paper weight conversion calculator.
Moisture Content: Paper is hygroscopic. High humidity can slightly increase the actual weight of physical sheets compared to the theoretical manufacturing specification.
Grain Direction: While grain direction doesn't change the weight calculation, it drastically affects the stiffness (rigidity) of the paper, often making "grain long" paper feel more substantial than "grain short" paper of the same weight.
Manufacturing Tolerance: Paper mills have a tolerance range (usually ±5%). A calculated 216 GSM might actually be manufactured as 210 GSM or 220 GSM in a specific batch.
Frequently Asked Questions (FAQ)
Why is 80 lb Cover heavier than 80 lb Text?
This is the most common confusion solved by a paper weight conversion calculator. "Cover" stock has a smaller basic size (20×26) than "Text" stock (25×38). Because the "lb" rating is based on 500 sheets of the basic size, 80 lb Cover is much thicker and heavier per square inch than 80 lb Text.
What is the difference between GSM and Lbs?
GSM (Grams per Square Meter) is a direct measurement of paper density and is constant regardless of sheet size. Lbs (Basis Weight) is the weight of 500 sheets of the paper's specific "Basic Size," which varies by paper grade.
Can I use this calculator for cardstock?
Yes. Cardstock is typically measured using "Cover" or "Index" weights in the US. Our paper weight conversion calculator includes both options.
What is a standard business card weight?
Standard business cards are usually 300 GSM or 350 GSM. In US terms, this converts to approximately 100 lb Cover or 130 lb Cover.
Is higher GSM always better?
Not necessarily. Higher GSM means heavier and thicker paper. While this implies quality for business cards or invitations, a high GSM would be disastrous for the pages of a 1000-page book, making it too heavy and hard to open.
How accurate is this conversion?
The math used in this paper weight conversion calculator is precise based on industry standards. However, physical paper manufacturing varies slightly between brands.
What is 20 lb Bond in GSM?
20 lb Bond converts to approximately 75 GSM. This is the standard weight for everyday office printing and copying.
Does paper color affect weight?
Generally, no. The dye used to color paper adds negligible weight. A 20 lb Bond paper weighs the same whether it is white, blue, or canary.
Related Tools and Internal Resources
Explore more tools to help with your printing and design projects:
Paper Thickness Chart – A visual guide comparing caliper thickness across different grades.
GSM vs Lbs Detailed Guide – An in-depth article explaining the history of these measurement systems.