Calculation of Sewing Thread Consumption for Garments

Sewing Thread Consumption Formula
Noor Ahmed Raaz
B.Sc. in Apparel Manufacturing
Asst. Merchandiser
Opex Sinha Group, Narayongonj

Sewing Thread Consumption
For Apparel Merchandising, in today’s competitive marketplace, there is a need for tight cost control. A realistic estimation of potential thread requirements for particular garment styles or contracts will not only end up saving money, and warehouse maintenance. As, if you buy sewing threads more than you require that will be a matter of extra warehouse maintenance. To understand sewing thread consumption we also need to understand the Seam and Stitch analysis.
Sewing thread
It's basic rule in garment industry that we must have knowledge how to calculate sewing thread consumption in 1 pcs garment then decide how many sewing thread we must buy for bulk production process.

For determining thread consumption there is a standard formula. In that formula you will get multiplying factors according to machine type and stitching classes. To define thread consumption you just have to multiply seam length with that factors. Thus, one can estimate total requirement of thread for making a garments. But actual thread consumption for a unit length of seam depends on many factors.

  1. Stitches per inches (SPI) 
  2. Stitch Classes
  3. Thickness of the seam (fabric thickness)
  4. Thread tension
  5. Thread count (thickness of sewing thread)
We should follow when calculate it with below steps :
  1. Measure the actual thread consumed in a specific length of seam along the garments.
  2. Calculate the thread consumption by using mathematic stitch formulas based on seam characters ( example : single stich, double stitch, chainstitch, overlock, etc ) also please take attentions in thickness of thread.
  3. Then convert it with total yardage contained in one cones of sewing thread & total quantity of garments.
Measuring Actual Thread Consumed
A specified length of the seam, for example 3 inches, is measured and then the thread is removed by carefully unraveling the stitch. You can then calculate the amount of thread consumed in one inch and multiply this factor times the total length of the seam measured in inches.

For example:
  • Length of seam is 42 inches or 1.17 yards.
  • Stitch and seam construction: 401 SSa-1.
  • Specified length of thread removed from a seam equals 3 inches.
  • Needle thread removed = 9 inches
  • Looper thread removed = 8 inches
  • Needle thread factor = 9 ÷ 3 = 3 inches of needle thread per inch of seam.
  • Looper thread factor = 8 ÷ 3 = 2.67 inches of looper thread per inch of seam.
  • Total needle thread consumed = factor 3 X 1.17yds = 3.51 yds
  • Total looper thread consumed = factor 2.67 X 1.17yds = 3.12 yds
  • Total Thread = 3.51 + 3.12 = 6.63 yards per seam.
  • Generally a 10 to 15% waste factor is added due to chaining-off, thread breaks, repairs, etc.
  • If a waste factor of 15% is selected then:
  • 6.63 yards/seam X 1.15 = 7.62 yards/seam including 15% waste factor.
Obviously you must do this for each seam to determine the total amount of thread consumed in the finished product.

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Mazharul Islam Kiron is a textile consultant and researcher on online business promotion. He is working with one European textile machinery company as a country agent. He is also a contributor of Wikipedia.

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