Paper Weight Calculator

What is Paper Weight?

Paper weight refers to the mass of paper per unit of area. It is a fundamental property that determines the paper's feel, durability, and suitability for different applications. However, the concept can be confusing because there are two primary systems for measuring it: Basis Weight (used mainly in North America) and GSM (Grams per Square Meter), the global standard.

• GSM (Grams per Square Meter): This is the most straightforward and universal measurement. It represents the mass (in grams) of a single sheet of paper that is one square meter in area. A higher GSM value means heavier and typically thicker, more durable paper. For example, standard office paper is often 80 gsm, while business cards are typically 300-350 gsm.
• Basis Weight (lbs): This system, common in the United States, is more complex. It is defined as the weight in pounds of a ream (500 sheets) of paper in its uncut, "basis" size. The complication is that the basis size varies depending on the type of paper (e.g., Bond, Text, Cover, Index). For example, the basis size for "Bond" paper (like office paper) is 17 x 22 inches, while for "Cover" stock (cardstock), it is 20 x 26 inches. This means that a "20 lb Bond" paper is not the same thickness or sturdiness as a "20 lb Cover" paper.

Because of this complexity, converting between Basis Weight and GSM is not a simple multiplication or division. The conversion depends on the paper type's specific basis size. Our calculator handles these complexities for you, allowing for easy and accurate conversions.

How to Use the Paper Weight Calculator

The Paper Weight Calculator is designed to simplify the conversion process between different paper weight standards. Here’s a step-by-step guide to using it effectively.

1. Enter the Paper Weight Value: In the input field, type the numerical weight of the paper you wish to convert. For instance, if you have standard office paper, you might enter "20".
2. Select the "From" Unit and Type: Use the first dropdown menu to select the unit you are converting from. This menu includes both GSM and various Basis Weight types (e.g., "lbs (Bond)", "lbs (Text)", "lbs (Cover)"). For our example of office paper, you would select "lbs (Bond)".
3. Select the "To" Unit and Type: Use the second dropdown menu to choose the unit you want to convert to. You can convert to GSM or any of the other Basis Weight types. For example, to find the universal standard weight, you would select "GSM (g/m²)".
4. Review the Result: The calculator will instantly display the converted weight. Converting "20 lbs (Bond)" will show a result of approximately 75.2 gsm. You can continue to change the "To" unit to see how that 20 lb Bond paper compares to other types, like Cover or Text stock.

The Formulas Behind the Conversion

The calculator uses specific formulas to convert between GSM and the various Basis Weight types. The core of the calculation is understanding the area of the basis ream for each paper type.

Formula to Convert Basis Weight (lbs) to GSM:

GSM = (Basis Weight in lbs / 500 sheets) * 453.592 g/lb / (Basis Sheet Width in inches * Basis Sheet Height in inches) * 1550 in²/m²

Simplified, this is:

GSM = (Basis Weight * 1406.1) / (Basis Sheet Area in in²)

Formula to Convert GSM to Basis Weight (lbs):

Basis Weight = (GSM * Basis Sheet Width in inches * Basis Sheet Height in inches) / 1406.1

Here are the standard basis sizes used in the calculator:

• Bond, Ledger, Duplicator: 17 x 22 inches (374 in²)
• Text, Book, Offset: 25 x 38 inches (950 in²)
• Cover: 20 x 26 inches (520 in²)
• Index: 25.5 x 30.5 inches (777.75 in²)
• Bristol: 22.5 x 28.5 inches (641.25 in²)

Practical Example

Let's consider a practical scenario. A small business owner in the U.S. is designing marketing flyers and wants them to feel substantial and high-quality. Their local printer suggests using "80 lb Text" paper.

Later, they decide to get a price quote from an online printer based in the UK. The UK printer's website lists paper options only in GSM. The business owner needs to find the equivalent of "80 lb Text" in GSM to ensure they order the correct paper.

1. Enter Value: They enter "80" into the calculator.
2. Select "From" Unit: They choose "lbs (Text)" from the dropdown menu, because they know Text paper has a specific basis size.
3. Select "To" Unit: They choose "GSM (g/m²)" to get the international standard measurement.

The Paper Weight Calculator instantly shows the result: 118.4 gsm (which would likely be rounded to the nearest standard, such as 120 gsm, by the printer).

Thanks to the calculator, the business owner can confidently order 120 gsm paper from the UK printer, knowing it will have the same weight and feel as the "80 lb Text" paper recommended by their local expert. This prevents costly mistakes and ensures the marketing materials meet their quality standards.

Further Reading

• Paper Weight Chart: Understanding Grammage and Basis Weight
• Wikipedia: Paper Density

Internal Links

• Paper Thickness Calculator
• Weight Converter
• Square Footage Calculator