If you are an experienced thermal paper buyer, you know that different paper grades have different lengths for the same paper roll size. For example, for 80mm x 80mm paper roll, our most popular paper size, can be anywhere from 50 to 90 meters long! Thicker materials tend to be more durable and are perceived by customers as of higher quality. However, the thicker the material, the less paper per roll, resulting in fewer receipts that can be printed, which means you have to change the paper roll frequently in your printer.
Therefore, thickness and length are two key factors you should consider when buying paper rolls for your application. In this article, we will show you how to measure the paper thickness and how to calculate the paper roll length.
Materials:

 A Ruler
 A Gauge
Firstly, You Need to Know the Paper Thickness:
The best way to measure the paper thickness would be with a Micrometer or gauge, which comes in a few styles. You can tear some pieces of paper, choose at least 4 spots on the paper, and measure the thickness with your gauge (you can buy the gauge from us if you don’t have one). This will give you an average of a few location points and you will not capture a high or low spot.
If you don’t want to buy a gauge, just ask your supplier about the thickness. But make sure they don’t trick you!
Secondly, Do Some Simple Math Work:
From the above abstract sketch, we can see the paper roll is essentially a cylinder. We can use the ruler to measure the paper roll width, diameter, and core size:
 A: paper width
 B: paper diameter
 C: core outer diameter
 T: paper thickness
 L: paper roll’s length
From the formula of cylinder volume, we can get the equation below:
A × L × T = πB²A ⁄ 4 – πC²A ⁄ 4
After simplifying, we can get the result:
L = (B² – C²) * 0.785 ⁄ T
This means if we know the paper roll diameter, core size, and paper thickness, we can get the paper length. (P.S: The paper roll length has no relationship with the paper width, no matter it is an 80mm width or 57mm width paper)
Example 1:
For 80mm x 70mm x 13mm 60gsm thermal paper, the paper diameter (B) is 70mm, the core size (C) is 13mm x 17mm, and the 60gsm paper thickness (T) is 80um. Using the above formula, we can easily get the roll’s length is 45m.
Example 2:
For 57mm x 40mm x 13mm 55gsm credit card paper rolls, the paper diameter (B) is 40mm, the core size (C) is 13mm x 17mm, the 55gsm paper thickness (T) is 60um. Use the above formula, we can get the roll’s length is 18m.
Here Is an Easytouse Excel Tool for Calculating Paper Roll Length:
Download the paper roll length calculating tool
get it nowConclusion:
Don’t just pay attention to the price per roll, but also look at the cost per meter. The longer paper will be more costeffective for you. Always consider the thickness and length factors when buying paper rolls to make sure you are getting what you pay for! If you are still looking for more information about thermal paper rolls, please do not hesitate to contact us at [email protected].
Thanks for pointing out that you’ll be able to calculate the length of the paper on the roll if you know the roll diameter, core size, and paper thickness. I was trying to help my daughter with a project for school, and she needed a certain length of plastic film from a roll. I wasn’t sure how to calculate the length, so thanks for sharing this guide!
Thanks for your comment, Amy.
How to get um if we know the GSM. What is the formula? 48GSM is equal to ? um
48gsm paper is equal to 5055um. You can ask this data from your paper supplier or measure it with the gauge.
Its very helpful for me
I want to purchase a guage for thickness checking
Hello Mahendra, you can send an email to [email protected], let’s have a further discussion about your need.
Hlo what is the price of 3 inch paper roll at Indian price
Please message me at 9311006800
dear i want paper length i have only paper width & paper gsm
hello
i want formula how can i calculate paper length i have only paper gsm & paper width if any body know this matter pls let me
That is the um for 70 GSM
The thickness is 90um – 93um for 70gsm thermal paper.
Hellow how to calculate paper straw cost what is the formula