Paper & Price Calculators

Grammage Calculator

Do it for the Grammage!

Our converting character representing the Grammage Calculator


Find the weight in grams per square meter (GSM) for a ream of paper, based on its basis weight.

Basis Weight (lbs.) X 1406.5 / Basis size = GSM

The weight in grams per square meter (GSM) for a ream of 25 x 38” book paper that has a basis weight of 45 lbs. is: 45 x 1406.5 / (25 x 38) = 67 GSM


Among the most important aspects of ordering paper for your business is calculating grammage. The density of paper can help you determine what you can use the product for. You can use our grammage calculator to determine the ideal paper density, and therefore the right product, for your project.

What Is Grammage?

Paper grammage is used to describe the density of paper, and can help you know what kind of paper you need to order for a given purpose. For example, business cards tend to be printed on paper with a somewhat higher density, to ensure the paper doesn’t bend or rip when inside a pocket or wallet. In comparison, letterhead must be on the less-dense side, to make it easy to fold up into an envelope. 

For those of us who don’t remember geometry class (no shame in that!) density means mass per unit of area. To simplify this, the density of paper can be measured by grams per square meter (GSM). Even though paper can come in many different densities, here are some guidelines on grammage when you are ordering paper for your business. Let’s start with why it matters.

Why Is Grammage Important in Paper?

There are many reasons why this measurement is important when you’re buying paper. The density of paper significantly impacts how it looks and feels. With the right GSM measurement, you’ll be able to meet the needs of your employees and customers. Denser paper may also damage printers that are not designed for it, so you need to be aware of that as well.

How Do I Calculate GSM?

Find an awesome (and modest) paper company’s calculator! Check out ours above. Simply choose your paper grade and size from the drop-down menu and then fill in the basis weight in pounds. Press “calculate” and you’re good to go. 

If you really want to do the math, you can click “Show Formula.” You’ll discover that it’s Basis Weight (lbs.) multiplied by 1406.5 all divided by Basis size = GSM. But seriously, why would you do math if you didn’t have to? 

While the math behind GSM measurements can sometimes be tricky to understand, our grammage calculator gives you everything you need to purchase the right paper or paperboard for your business and brand.

Frequently Asked Questions about Grammage and our Grammage Calculator

Bring all your grammage questions here! We love to share our paper knowledge!

What Does Higher or Lower Grammage Mean?

When you’re obtaining GSM measurements, keep in mind that higher numbers indicate that the paper is denser. Denser paper can be harder to fold, but is also more durable and therefore more resistant to creasing. The bottom line is that paper with a higher GSM versus a lower GSM will be hard to determine until you know what you want to use the paper for. Not to sound like a broken record here, but if you want to calculate the grammage of the paper you have in mind, you can definitely count on our calculator!

What Is Normal Paper Grammage?

As with pretty much every paper metric, “normal” grammage depends on the kind of paper you’re talking about. What counts is whether the grammage matches what would work well with what you’re using the paper for. The paper that is often made into price lists and forms is too thin to be used for brochures.

Use our grammage calculator to identify the grammage of your paper and then you can determine if it meets your intended specifications or whether a different paper would be more suitable. 

What Is the GSM of Paper and Paperboard?

Paperboard is a type of material that is denser than paper. There actually isn’t a hard and fast rule that establishes a clear differentiation between paperboard and paper, when it comes to grammage. It is possible for paperboard to be either single-ply or multi-ply.  

Since paperboard is often used to make packaging materials, this board is easy to cut and form into different shapes. The material is highly versatile, as is paper, so you need to have a good sense of the density you are looking for before you determine what grammage you need. If you want to know the density in GSM of a particular product, we recommend using our calculator above!

Is Grammage the Same as Basis Weight?

There are two basic measurements that are commonly used to measure paper’s density:GSM and basis weight. GSM measures the density in grams per square meter. By contrast, the mass per number of sheets of a specific paper size is known as basis weight. Basis weight may be more commonly found in the United States and other countries that use United States paper sizes, whereas you will see grammage, particularly on spec sheets and paper product labels, throughout the world.

The good news is that if you do need to know the basis weight of paper, we have a calculator for basis weight as well! However, when you get there you might be surprised to discover that you need to know the grammage (GSM) in order to calculate basis weight. Good thing our calculators can be used together!

Who Made This Useful Grammage Calculator? 

Pleased to meet you! Allow us to introduce ourselves. We’re Case Paper, a premium paper company that has been in operation for over 80 years! We devote ourselves to being “On the Case” for our customers, so whatever you need, just let us know! Feel free to check our other paper resources while you’re here. We’ve got a lot of calculators and tables to get you the information you need.

Find the Premium Paper You Need with Case Paper!

We’re so glad you found our grammage calculator and we hope it works well for you! Don’t forget, though, that only your Case Paper representative can price your premium paper order for you. Contact us today to work with a representative who will customize your order to make sure you get exactly the amount and type of paper needed for your project.