How to Calculate Thread Consumption in Garment Industry?

Accurately calculating thread consumption is essential for garment manufacturers to optimize production costs, prevent wastage, and ensure efficient use of resources. The amount of thread required varies depending on the type of garment, fabric, stitch types, and production methods. 

In this blog, we will provide a detailed guide on how to calculate thread consumption for garments, with practical tips and examples.

Why Calculating Thread Consumption is Important

1. Cost Management

   Precise thread consumption calculations help in estimating the cost of production and prevent overordering or underordering thread supplies, keeping expenses in check.

2. Waste Reduction

   Overestimating thread usage can lead to unnecessary wastage, while underestimating may result in production delays. Accurate calculations minimize both scenarios.

3. Production Efficiency

   Knowing the exact thread requirements ensures that the sewing process runs smoothly, without interruptions due to shortages or excess inventory.

Factors Affecting Thread Consumption

1. Type of Garment

   Different garment styles, such as shirts, trousers, and jackets, have varying thread requirements based on their complexity and stitching needs.

2. Stitch Type

   The type of stitches used—such as lockstitch, overlock, or chainstitch—affects thread consumption. Overlock stitching generally uses more thread than lockstitch due to its loops and additional strands.

3. Fabric Type and Thickness

   Heavier fabrics like denim and canvas require more thread compared to lightweight fabrics like cotton or polyester due to the need for stronger stitching.

4. Seam Length

   Longer seams require more thread. The overall seam length of a garment needs to be calculated accurately to estimate the thread usage.

5. Stitch Density

   Stitch density, or stitches per inch (SPI), influences the amount of thread consumed. Higher SPI means more stitches, and thus more thread.

Step-by-Step Process for Calculating Thread Consumption

1. Measure the Seam Lengths of the Garment

Begin by measuring the length of all the seams in the garment. This includes all seams for assembly, hemming, finishing, and any decorative stitching.

Example:

• A basic T-shirt has the following seam lengths:

  • Shoulder seams: 40 cm (total)
  • Side seams: 100 cm (total)
  • Sleeves: 50 cm (total)
  • Hemming: 90 cm (total)
  Total seam length: 
  $40+100+50+90=280\text{ cm}$

2. Choose the Stitch Type

Identify the type of stitch used for each seam. Different stitch types have different thread consumption rates. Below are common stitch types and their approximate thread consumption factors:

• Lockstitch: 2.5 times the seam length
• Overlock (3-thread): 5 times the seam length
• Chainstitch: 3 times the seam length

3. Calculate the Thread Consumption per Seam

For each seam, multiply the seam length by the thread consumption factor of the stitch type used.

Example:

• Shoulder seams (lockstitch):
  Thread consumption = Seam length × 2.5
  $40\text{cm}\times 2.5=100\text{cm}\text{ of thread}$

• Side seams (lockstitch):
  $100\text{cm}\times 2.5=250\text{cm}\text{ of thread}$

• Sleeves (overlock):
  $50\text{cm}\times 5=250\text{cm}\text{ of thread}$

• Hemming (lockstitch):
  $90\text{cm}\times 2.5=225\text{cm}\text{ of thread}$

4. Sum the Total Thread Consumption

Add the thread consumption for all seams to get the total thread requirement for the garment.

Example:

• Total thread consumption:
  $100+250+250+225=825\text{cm}\text{of thread}$

5. Add a Wastage Factor

To account for wastage during sewing, thread changes, and machine setup, add a wastage factor (typically 10%) to the total thread consumption.

Example:

• Wastage factor:
  $8.25\text{meters}\times 10\%=0.825\text{meters}$

• Total thread consumption with wastage:
  $8.25+0.825=9.075\text{meters}$

Thread Consumption for Different Stitch Types

To give a broader overview, here are the approximate thread consumption factors for common stitch types used in garment manufacturing:

• Single Needle Lockstitch: 2.5 times the seam length
• Overlock (3-thread): 4-5 times the seam length
• Overlock (4-thread): 5-6 times the seam length
• Chainstitch: 3 times the seam length
• Coverstitch (2-needle): 4-5 times the seam length
• Flatlock (3-thread): 5-6 times the seam length

Tips for Accurate Thread Consumption Calculation

1. Use Software Tools
   Consider using software tools that can calculate thread consumption based on predefined garment templates and stitch types. This helps streamline the process and reduce human error.

2. Account for Thread Shrinkage
   Some threads may shrink slightly during washing or finishing. Account for this when calculating thread consumption, especially for natural fibers like cotton.

3. Perform Sample Testing
   Before large-scale production, perform thread consumption tests on sample garments to get a more accurate estimate.

4. Regularly Update Calculations
   As garment designs, fabrics, or stitching techniques change, update your thread consumption calculations to reflect the new requirements.

Conclusion

Accurately calculating thread consumption for garments is an essential aspect of production planning. By understanding factors such as seam length, stitch type, and stitch density, you can estimate thread requirements efficiently and avoid costly mistakes in production. 

Following this guide will help garment manufacturers optimize their thread usage, reduce wastage, and maintain cost-effective production processes.