Skip to Content
​Fabric Math
​Numbers that Make Fabric

​ ​​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Thread count
The count of a fabric (like 120, 60, 40, etc.) indicates the thickness and fineness of the yarn.  

A higher count number means finer(thinner) thread and a tighter, smoother weave.

So, When yarn thickness increases, the number of threads that fit within a square inch decreases.
This count represents the combined number of warp and weft threads per square inch.


  Higher count = finer, smoother fabric.
Lower count = thicker threads, more durable.



Thread CountFeelUse
40–60Thick, durableUpholstery, shirts
80–100Medium softDresses, premium shirts
120–200+Luxurious, fineHigh-end bedding, suits

Warp and Weft
Warp (Lengthwise Threads)
Warp threads run vertically (top to bottom) on the loom.
They are strong, tightly stretched, and fixed during weaving.
Along the length of the fabric (called the warp direction).


Weft (Crosswise Threads)
Weft threads run horizontally, interlacing over and under the warp threads.
Inserted during weaving, usually by a shuttle or air jet.
Across the width of the fabric (called the weft direction).


warp yarns are stronger and smoother than weft yarns.
Usually fewer threads per inch than warp (PPI – picks per inch).

W W W W W W W  (Warp threads)
- - - - - - - - - - - -     (Weft threads passing through)



The vertical lines are called Warp.
The Horizontal lines are called Weft.
Warp = they hold the structure, under tension.
Weft = Left to right, they go across.



EPI (Ends Per Inch)
PPI (Picks Per Inch)

​EPI and PPI — two key measures that describe how tightly a fabric is woven

​EPI and PPI — The Density of a Woven Fabric
​When you look at woven fabric under magnification, you’ll see many interlaced threads — some vertical, some horizontal.

If a cotton fabric has:

  • EPI = 100, and

  • PPI = 80

    then the fabric count = 100 × 80

    This means it’s a tightly woven fabric, likely smooth and strong.




EPI = Ends = Warp
PPI = Picks = Weft 
EPI + PPI = Thread Density


Example: If a fabric has 60 weft threads in one inch, it’s called 60 PPI.

EPI (Ends Per Inch) The number of warp threads (the vertical ones) in one inch of fabric width.
“Ends” means the warp yarns.

PPI (Picks Per Inch) The number of weft threads (the horizontal ones) in one inch of fabric length.
“Picks” means the weft yarns.

PropertyEPI (Ends per Inch)PPI (Picks per Inch)
DirectionWarp (Lengthwise)Weft (Crosswise)
IndicatesWarp thread densityWeft thread density
UnitThreads per inchThreads per inch
AffectsStrength, smoothnessFlexibility, softness
Controlled byLoom setting (reed)Shuttle/Weft insertion speed



Thread Density

    Thread density is the total number of warp and weft threads packed into a specific area of fabric — usually one square inch.
    When It tells us how tightly the threads are woven together. It’s a key factor that affects a fabric’s strength, texture, thickness, and appearance.
    Thread Density = EPI + PPI
    Fabric Count = EPI × PPI

    If a cotton fabric has:


  • EPI = 120, and

  • PPI = 100

Then:

  • Thread density = 220 threads per inch (TPI)

  • Fabric count = 120 × 100 = 12,000 intersections per square inch

This means it’s a fine, tightly woven, smooth fabric — like high-quality bedsheets or shirting cotton.


High vs Low Thread Density

Thread DensityFabric TypeCharacteristics
Low (e.g., 40×40)Muslin, canvasLoose weave, breathable, rougher
Medium (e.g., 80×60)Regular cottonBalanced strength & comfort
High (e.g., 120×100)Fine cotton, poplinSmooth, durable, refined
Very High (e.g., 200×200)Luxury sateen/sheetsSilky, dense, soft




GSM in Fabric

    GSM stands for Grams per Square Meter.

    It measures the weight of the fabric — not its thickness directly, but how heavy or dense it is per square meter of area.

    GSM tells you how heavy or light a fabric feels.

    GSM helps you understand:

  • How thick or thin a fabric is

  • How durable or breathable it will feel

  • What the best use of the fabric is (summer shirt vs winter hoodie)


    • GSM = weight of fabric in grams ÷ area of fabric in m²

    GSM =  Weight (g) / Area (m²)

  • If a 1m × 1m piece of fabric weighs 150 grams,

    GSM = 150


    • Fabric TypeTypical GSMFeel / Use
    Lightweight fabrics60–150 GSMSoft, airy – shirts, blouses, lining
    Medium-weight fabrics150–250 GSMDurable – trousers, dresses, T-shirts
    Heavyweight fabrics250–450+ GSMThick, warm – denim, jackets, upholstery
    Knitted fabrics (T-shirts, hoodies)120–300 GSMVaries with thickness & warmth
    Bedsheets / cotton sateen100–250 GSMSoft, breathable, smooth