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2 Best Ways To Calculate The Fabric Density

What is fabric density?

Fabric density is the combination of warp density and weft density. The total numbers of warp and weft yarn in a certain area. And the measurement unit is in inch.

For example, like some cotton fabric, supplier will mention “40*40/128*68”. 40 is the yarn count, the thickness of a single yarn. (I will write a post about the yarn count later. ) 128*68 is the density. Normally we write warp density first. And regularly the warp density is higher than the weft density. So 128 means there’re 128 warp yarns per 1 square meter.

How to calculate fabric density?

After talking about the definition, let me share with you the easiest way to calculate the fabric density.

Tool we need to use.

Now I will use a tool which was mentioned in my previous post. The density mirror. You can find it in the below photo.

Density Mirror
Density Mirror

By using a density mirror, we can easily see the density by our eyes. No need to calculate in a complex way. The result is an idea one, not accurate enough. But it’s already enough for us.

Does this tool can read all kind of fabric density?

The answer is no. Only plain fabric can be read by this mirror. If the fabric is satin or twill, we can reverse to the back side and read the density. But normally it’s hard to read. And we will use another tool. A density magnifier. (See this tool in below photo.)

Numbers on Density Mirror
Numbers on Density Mirror

How to use a density mirror?

You may see from the photo it contains several pieces. Why? Because the fabric density will be different from very low to extremely high. Each piece has the limit to use on a specific range of the density.

It has 2 sides with numbers on each side like a ruler. Each number on the ruler means the yarn quantity. We usually calculate fabric density in inch. Some density mirror only has cm. So we have to calculate it into inch. But mine mirror has both in cm and inch. So I can directly read the inch. No need to convert again.

The number on the mirror is different. That’s right! The mirror with big number is for high density fabric and the small number is for low density fabric.

For example, you can put it both vertical or horizontal way on the fabric as you wish. After that, please focus on the line part of the mirror. The eye is better on the 45-60 degree angle against the mirror. In this position, you will easily see a diamond shape on it. (Check out the below photo.)

Diamond Shape
Diamond Shape

Sometimes it’s not a perfect diamond share. You need to adjust the mirror little bit to make the diamond shape perfectly. Now you are very close to the density you want to know. The diamond angle point to the ruler is the yarn quantity. You can choose the upper number in cm or the down number for per inch. Then, you change the mirror position on the other way to read the number again.

Density mirror is a good tool to identify the fabric warp and weft.

For example, the number of the fabric on my hand is 28 and 26. From the previous point, the bigger number is the warp.

Maybe you will suddenly notice it’s also a very good way to identify the warp and weft of the fabric. Bingo! You got my idea! (How to identify the fabric warp and weft? Click and check.)

Fabric density calculation formula.

Here is the last step. To calculate the density.

The density we see from the mirror is 28 and 26 per cm. So you can put in the following formula and get the result.



The final density in inch is around 71*66.

If the mirror on your hand same as mine. You can read the inch ruler to get the result immediately.

How to use a density magnifier?

First, let’s see what is the density magnifier. It’s the tool in the following photo.

Density Magnifier
Density Magnifier

It has a four sides with ruler and a needle which you can move it by the knob.

The four sides ruler are in the same length. 1 inch.

When the fabric is satin surface or twill you can use this magnifier to count the yarn quantity in a certain area. After that you will get the density you want. It’s also an easy way. The magnifier has LED. The below photo shows the vision through it.

Vision Under Magnifier
Vision Under Magnifier

These are the 2 best ways to calculate the fabric density. You can read almost all fabric density by these 2 tools.

Want to know more knowledge about textile. Stay tuned for our next post.

2 thoughts on “2 Best Ways To Calculate The Fabric Density”

    1. Hi MD. Shakib Biswas,

      By using the density mirror to check the fabric density is mostly for woven fabric. Here is the way to check the knit fabric density. Please kindly check.

      To check the density of a weft knit fabric, you can follow these steps:

      Lay the fabric flat: Start by laying the fabric on a flat surface, such as a table or a cutting mat.

      Prepare a ruler: Get a ruler with clear markings in centimeters or inches, depending on your preference.

      Determine the measurement area: Decide on the area of the fabric you want to measure. It is recommended to choose a representative section that is free from any distortions or irregularities.

      Align the ruler: Place the ruler on the fabric, aligning one edge of the ruler with the starting point of the measurement area.

      Count the wales: A wale is a column of stitches running lengthwise in the weft knit fabric. Count the number of wales within a known length, such as one inch or one centimeter. Ensure that you count only complete wales and exclude any partial ones at the edges.

      Measure the course length: A course is a row of stitches running crosswise in the weft knit fabric. Measure the length of the course in the same area where you counted the wales. You can use the ruler to measure the distance between two consecutive courses.

      Calculate the density: To calculate the density, divide the number of wales by the length of the course. For example, if you counted 15 wales in one inch, and the course length is 2 inches, the density would be 15 wales per 2 inches.

      Repeat for accuracy: It is a good practice to measure multiple areas of the fabric and take an average to get a more accurate density measurement.

      Remember that the density of a weft knit fabric can vary across different areas, so it’s important to take multiple measurements and calculate the average to get a representative value.

      Hope it’s clear for you.

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