Sewing Thread Consumption Formula with Example for Garments
Noor Ahmed Raaz
Faculty Member, Dept. of Textile Engineering,
Atish Dipankar University of Science & Technology
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.
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 factor. 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.
- Stitches per inches (SPI)
- Stitch Classes
- Thickness of the seam (fabric thickness)
- Thread tension
- Thread count (thickness of sewing thread)
It is essential to know the consumption of sewing thread in a garment to:
- Estimate the number of cones needed.
- Calculate the cost of sewing thread required to produce the finished product.
We should follow when calculate it with below steps:
- Measure the actual thread consumed in a specific length of seam along the garments.
- Calculate the thread consumption by using mathematic stitch formulas based on seam characters (example : single stich, double stitch, chain stitch, overlock, etc) also please take attentions in thickness of thread.
- Then convert it with total yardage contained in one cones of sewing thread & total quantity of garments.
Thread consumption can be determined in numerous ways such as:
- Determining the actual amount of thread consumption in a particular length of seam.
- Calculating the thread consumption by using stitch formulas.
- Calculating the thread consumption via thread consumption estimates.
Measurement of Actual Sewing Thread Consumption
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.
- 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.
Determination of Thread Consumption Using Thread Consumption Ratios
A simple technique of calculation of thread consumption is to utilize the standard thread consumption ratios for a range of stitch classes as given in Table.
Table: Thread Consumption Ratio for Various Stitch Types
|Type of Stitch||Thread Ratio||No. of Needles||Needle Thread%||Looper Thread%|
|101 – Chainstitch||4.0||1||100||0|
|301 – Lockstitch||2.5||1||50||50|
|304 – Zigzag Lockstitch||7.0||1||50||50|
|401 – Two Thread Chain Stitch||5.5||1||25||75|
|406 – Three Thread Covering Stitch||18.0||2||30||70|
|503 – Two Thread Overedge Stitch||12.0||1||55||45|
|504 – Three Thread Overedge Stitch||14.0||1||20||80|
|602 – Four Thread Covering Stitch||25.0||2||20||80|
|605 – Five Thread Covering Stitch||28.0||3||30||70|
Note: The thread ratios are attained by considering a stitch density of 7 stitches/cm.
By connecting these thread consumption ratios to the seam length using each stitch type, the total thread consumption could be determined.
- Length of seam = 220 cm
- Stitch class 301 = Single thread lock stitch
- Thread ratio obtained from the table (thread length per cm of seam) = 2.5 cm
- Total sewing thread consumption = 220 × 2.5 = 550 cm
- Consumption of needle thread = 1210 × 0.25 = 275 cm
- Consumption of looper thread = 1210 × 0.75 = 275 cm
- By adding 15% wastage = 550 × 1.15 = 632.5 cm of thread per seam
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.