How to Find Fabric EPI and PPI by Yourself?

Do you need to know the EPI and PPI of woven fabrics at the time of fabric sourcing? And want to be ensured yourself that you have received right fabric in terms of fabric construction. You can do that just by siting on your chair.

For newbie, EPI stands for Ends per inch and PPI stands for Picks per inch. Where Ends is known as Warps and Pick are known as weft yarn. 

Being an merchant and sourcing professional, if you don’t know how to find EPI and PPI yourself you may need to send fabric sample to testing lab. In case, factory has its in-house testing lab then it is ok. You would get the information of fabric sample EPI and PPI on the same day. But when you need to send sample to outside lab, it would cost you money and has to wait for at least one day. 

There is a very simple method to find fabric EPI and PPI without any special testing instruments. If you want to know how to find that continue reading. 

There is one difficult thing to know exactly what are the warp and wefts in fabric. Use our guide to identify warp and weft in a woven fabric. In most fabrics EPI is higher than PPI.

Step 1: Collect fabric swatch

Collect fabric swatch for which you are going to find EPI and PPI. Lay fabric sample on a flat table and remove all creases by hand press. Mark arrows for warp and weft direction if you know.

Step 2: Make a square of one sq.inch on the sample  

Mark a square of 1 X 1 inches on the fabric using pen or pencil. Try to marks lines parallel to warp and weft direction. Cut 5 squares from different place of the sample to calculate average EPI and PPI.

Step 3: Count number of ends and Picks inside those squares. 

In case yarns are thicker and visible with open eyes count numbers of Ends and picks using a needle or a pin. In case, yarns in the fabrics are not visible and not possible to count with open eyes, pull out warp and weft yarns one by one from the cut squares. Count numbers of yarns you get form one inch length and width of fabric.

Using same method, find EPI and PPI from all 5 samples and calculate average EPI and PPI.


Example:

Fabric sample

I have shown you an example of loosely woven fabric in the right side image. On that fabric sample, a 1” X 1” square is made. The vertical laid yarns are ends (warp) and horizontal yarns are picks (wefts). Here you can counts ends and picks without any pick glass as the sample fabric is loosely woven. In one inch length there is 9 ends and 8 picks.

So EPI and PPI of this sample is 9 and 8 respectively.